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Geology of the Morpeth district Sheet description of the British Geological Survey 1:50 000 Series Sheet 14

By B Young and D J D Lawrence

Bibliographical reference: Young B and Lawrence, D J D. 2002. Geology of the Morpeth area. Sheet description of the British Geological Survey, 1:50 000 Series Sheet 14 Morpeth (England and Wales).

Geology of the Morpeth district. Sheet description of the British Geological Survey 1:50 000 Series Sheet 14 Morpeth (England and Wales)

Author: B Young and D J D Lawrence

Contributors: B Beddoe-Stephens P J Brand, M T Dean’ L J Donnelly, G S Kimbell and N S Robins. Keyworth, Nottingham, British Geological Survey, 2002.

Keyworth, Nottingham British Geological Survey 2002. © NERC 2002. All rights reserved. ISBN 0 85272 443 8

The National Grid and other Ordnance Survey data are used with the permission of the Controller of Her Majesty’s Stationery Office. Licence No: GD 272191/2002 Maps and diagrams in this book use topography based on Ordnance Survey mapping.

© NERC 2002. All rights reserved. Copyright in materials derived from the British Geological Survey’s work is owned by the Natural Environment Research Council (NERC) and/or the authority that commissioned the work. You may not copy or adapt this publication without first obtaining permission. Contact the BGS Intellectual Property Rights Section, British Geological Survey, Keyworth, e-mail ipr@bgs.ac.uk. You may quote extracts of a reasonable length without prior permission, provided a full acknowledgement is given of the source of the extract.

(Front cover) Cover photographThe imposing crenellated tower of Belsay Castle [NZ 0848 7855] is one of the finest surviving examples of a medieval border tower house. Adjoining it on the left is the roofless ruin of the Jacobean manor house. Both the castle and manor house are built of a medium-grained sandstone, quarried locally from a thick sandstone unit that overlies the Corbridge (Lower Felltop) Limestone of Namurian age (D5174). (Photographer T S Bain.)

(Back cover)

Acknowledgments

This description was compiled by B Young. The major part of the text was written by B Young and D J D Lawrence. It was edited by D J Fettes and A D McAdam.

Palaeontological and biostratigraphical contributions were made by P J Brand and M T Dean. B Beddoe Stephens provided descriptions of intrusive igneous rocks, G S Kimbell prepared the chapter on concealed rocks and geophysics, L J Donnelly provided information on engineering geology, and N S Robins contributed the section on water resources.

The assistance of numerous land owners during the course of the survey is acknowledged. The management of North Tyne Roadstone Ltd are thanked for facilities provided in the survey of Mootlaw Quarry. A Pringle is thanked for making available fossil specimens from his personal collection.

Notes

The word ‘district’ is used in this sheet description to denote the area included in the 1:50 000 geological Sheet 14 Morpeth. National Grid references are given in square brackets throughout this description. Unless otherwise stated, all lie within the 100 km square NZ. Numbers preceded by the letter E refer to the BGS sliced rock collection.

Geology of the Morpeth district—summary

The Morpeth district lies in south central Northumberland. The western three-quarters of the district is predominantly agricultural with a widely scattered population. The eastern portion of the district forms part of the Northumberland Coalfield. Although deep mining has now ended within the district, the industry has left an indelible legacy on the landscape including former mining settlements such as Bedlington, Seaton Burn and Burradon. Communities such as Coxlodge, South Gosforth and Long Benton are now merged with the Newcastle upon Tyne conurbation to the south. The new town of Crammlington was developed in the 1950s from a small village. The ancient market town of Morpeth is an important commercial and market centre which, with County Hall, today is the administrative centre of Northumberland.

The oldest rocks in the district are of Lower Carboniferous age. These crop out in the extreme western part of the district. They are succeeded eastwards by progressively younger Carboniferous rocks, all of which dip gently towards the North Sea. The Carboniferous rocks of the Morpeth district form part of the Solway-Northumberland Trough. This may be regarded, in simple terms, as a broad half-graben basin with a comparatively thick succession of Carboniferous sediments, lying between the Alston Block on the south and the Southern Upland and Cheviot massifs to the north. During Carboniferous times, subsidence, and thus sedimentation, within this trough was largely controlled by contemporaneous extensional movement along the Stublick-Ninety Fathom Fault System which forms the northern boundary of the Alston Block. This was one of the most important structural influences in the geological evolution of northern England. It seems likely to be a structure inherited from the Iapetus Suture, the line of closure of the former continents of Laurentia to the north, and Avalonia to the south.

Structural control of sedimentation was most pronounced in earliest Carboniferous, Dinantian, times during deposition of the Liddesdale Group. This consists of a series of rhythmic units, or cyclothems, each typically comprising marine limestone succeeded in turn by marine mudstone, nonmarine sandstone and in places seatearth and coal.

During the Silesian, these marine influences became progressively more subordinate as nonmarine deposition became dominant through the Stainmore Group, culminating in the widespread development across much of northern England, of the deltaic plains and forest swamps of the Coal Measures.

Continued extensional movement related to parts of the Iapetus Suture Zone during Late Carboniferous-Early Permian times caused tilting and faulting of the Carboniferous rocks, and allowed the widespread intrusion of the tholeiitic dolerite of the Whin Sill. This suite of intrusions, the original sill of geological science, crops out in the extreme west of the district but is almost certainly present beneath much of the district.

Apart from some further slight flexuring and faulting in post-Permian times there are no deposits or structures to record the district’s geological history until the Palaeogene. At this time tensional stresses associated with the volcanic provinces of the Hebrides caused fracturing and intrusion of tholeiitic dykes across much of northern Britain, including the Morpeth district.

Throughout much of the district, solid rocks are concealed beneath a mantle of superficial deposits of Quaternary age. Whereas it is likely that the district experienced several periods of glaciation, the deposits and landforms seen today date from the latest, Late Devensian, glaciation. Till, or boulder clay, is the most widespread deposit though small areas of glaciofluvial and glaciolacustrine deposits are present locally. Postglacial and recent deposits include alluvium, river terrace deposits and peat.

Although coal has been by far the most important mineral product of the district, several other minerals have been worked: large-scale limestone quarrying continues today. The section on Applied geology describes the geological resources of the district and the relevance of the geology to planning and future development, with particular emphasis on the importance of issues arising from former mineral extraction. Information sources list BGS data and other holdings relevant to the district; a bibliography is also provided.

(Table 1) Geological succession in the Morpeth district.

Chapter 1 Introduction

The Morpeth district, described here, lies in south central Northumberland. The geology of the district is depicted in simplified form in (Figure 1). The land rises very gradually westwards from the gently undulating coastal plain bordering the North Sea, at elevations of between 15 and 100 m, to the low hills in the west which locally reach over 210 m (Figure 2). Drainage is entirely to the North Sea, principally by way of the River Wansbeck in the north, and the River Blyth and its major southern tributary, the River Pont, in the central and southern part of the district. In the extreme west, several streams flow westwards to join the River North Tyne. Smaller streams in the south, including the Ouse Burn, are tributaries of the main River Tyne.

The western part of the district, which is underlain by Carboniferous rocks of the Liddesdale and Stainmore groups (Visean to Namurian), is predominantly agricultural with sheep and cattle farming on extensive areas of permanent pasture, passing eastwards into more extensive arable land use. In these areas population is widely scattered in numerous farms and tiny hamlets with small, but important, centres of population in villages such as Kirkwhelpington, Great Whittington, Matfen, Stamfordham and Whalton. Large country houses with their surrounding estates, which are such important features of the landscape of rural Northumberland, include Wallington, Belsay, Capheaton and Kirkley halls; the last is now the Northumberland College of Agriculture.

The eastern portion of the district forms part of the Northumberland Coalfield, composed of Coal Measures rocks. Although mining has now ended, the industry has left an indelible legacy on the landscape. Most colliery buildings have been demolished and spoil heaps landscaped, often in conjunction with recent opencast coal extraction. Remains of abandoned colliery railways may still be traced and areas of subsided ground above old workings may be seen locally. Bedlington, Dudley, Seaton Burn and Burradon are old coal mining settlements. Other former mining communities, including Coxlodge, South Gosforth and Longbenton, are now merged within the Newcastle upon Tyne conurbation. The village of Crammlington was the basis of a ‘new town’ developed in the 1950s. The ancient market town of Morpeth, at the northern extremity of the district, still serves as an important market and commercial centre and, with County Hall, is today the administrative centre of Northumberland. The predominantly agricultural character of much of the district has, in recent years, been somewhat modified as isolated farm houses and many of the villages have become popular residential areas for the major urban centres of Tyneside. The old village of Ponteland has, with the adjoining extensive estate of Darras Hall, long been an important dormitory settlement.

Despite the long history of mineral extraction, this is today limited to the quarrying of limestone at Mootlaw, near Matfen. Exploration for further reserves of opencast coal is understood to be in progress.

History of survey

Primary geological surveying was undertaken by H H Howell, W Topley, G A L Lebour and G Barrow, with the first results published as Sheet 105NW, Old Series, in 1892. A revision survey, undertaken between 1922 and 1937 by W Anderson, G A Burnett, V A Eyles and A Fowler, was published as Sheet 14 Morpeth in 1955. This was reprinted twice, the last time in 1970. Small areas along the western, southern and eastern margins of the district were resurveyed between 1959 and 1983 as part of the revision survey of Sheet 13 Bellingham, Sheet 20 Newcastle and Sheet 15 Tynemouth. Systematic revision of the coalfield areas of the district was begun in 1983 by I Jackson, D V Frost and D J D Lawrence as part of a programme of surveys commissioned by the Department of the Environment to provide modern geological and thematic maps for the region with particular attention directed towards aspects of land-use planning. Resurvey of the Liddesdale and Stainmore Group outcrops was carried out by B Young and D J D Lawrence between 1994 and 1996.

These modern surveys have incorporated a huge volume of new data including the results of extensive exploration for opencast coal resources, site investigations and some geophysical surveys. These and other relevant data sources are listed in the chapter on Information sources.

Geological history

The geological succession of the district is summarised in (Table 1). The oldest rocks that crop out within the district belong to the Lower Carboniferous (Dinantian). The regional setting indicates that a considerable thickness of older Carboniferous rocks is present at depth, though nowhere in the district has the total thickness of this Carboniferous sequence been proved. The nature and age of the sub-Carboniferous basement beneath the district is unknown. However, by extrapolation from areas to the north and south it is probably made up of Ordovician-Silurian strata, similar to those of north Northumberland and the Southern Uplands, and possibly also with some Old Red Sandstone.

During early Carboniferous times the area which was to become northern England consisted of a series of fault bounded blocks and basins. This broad structural setting is today generally regarded as having formed within a crustal stress field in which north-south tension was dominant (Leeder, 1982; Kimbell et al., 1989; Fraser and Gawthorpe, 1990; Chadwick et al., 1995). At that time much of central Northumberland, including the Morpeth district, lay within the Solway-Northumberland Trough. This may be envisaged in simple terms as a broad roughly east-west-orientated halfgraben basin lying north of the Alston Block, and separated from it structurally by the east-west-trending Stublick-Ninety Fathom Fault System. To the north lay the massifs of the Southern Uplands and Cheviots. The northern margin of the trough is also marked by a belt of roughly east-west major contemporaneous fault lines, though these are of much more modest proportions than those on the southern margin.

The Stublick-Ninety Fathom Fault System, one of the most important structural influences in the geological evolution of northern England, controlled sedimentation in the region throughout much of early Carboniferous times. Geophysical studies have related this fracture system to the Iapetus Suture, the line of closure of the former northern continent of Laurentia and the southern continent of Avalonia (Chadwick et al., 1995). The exact position of the suture line is uncertain, though it is believed to lie to the south of the Lower Palaeozoic outcrops of the Southern Uplands and north of the outcrops of rocks of similar age in the Lake District. The Stublick-Ninety Fathom Fault System is thought to have developed in the early Carboniferous as a result of extensional reactivation along the suture zone, in the hanging-wall block (Chadwick and Holliday, 1991). The persistence of the Alston and Southern Upland block areas as structural highs throughout much of Carboniferous times has been attributed to the buoyancy afforded to them by the Caledonian granite intrusions (Leeder, 1982).

Basin development and sedimentation were influenced throughout the Carboniferous by movement along the major east-west faults, particularly the Stublick-Ninety Fathom fault system. Such subsidence was much more rapid in the early to mid-Dinantian during a rapid extensional phase of basin development (Leeder and McMahon, 1988; Kimbell et al., 1989). Rates and amounts of subsidence appear to have declined markedly throughout the late Dinantian and Namurian post-extensional phase of basin development, though these effects probably continued to influence sedimentation into Westphalian times.

This overall structural regime exerted a marked influence upon the complex interplay of marine and nonmarine environments, which characterised the Carboniferous. In early Carboniferous times, differential subsidence between fault blocks caused a progressive submergence of much of the region beneath a wide, shallow tropical sea.

During the early Carboniferous, the Liddesdale Group was deposited in an extensive, low-lying deltaic swamp, which was subject to periodic incursions of marine water. During periods of relatively slow subsidence, progradational building of the delta, mainly from the north and north-east, resulted in the deposition of freshwater muds and silts, followed by the accumulation of sheet-like, and locally channel-filling, bodies of sand. On occasions the delta surface was built up to above sea level, allowing the development of swamp forests. The soils on which these grew are seen today as seatearths; the vegetation is locally preserved as thin coal seams. Repeated marine incursions, mainly from the south, apparently during periods of more rapid subsidence, spread warm clear water across the district, in which marine limestones and some marine shales were deposited. The repetition of this pattern of sedimentation led to the development of the cyclic succession of rocks, known from their extensive development in North Yorkshire as Yoredale cyclothems. The nature and possible origin of these cycles has been the subject of work by numerous authors e.g. Dunham (1950; 1990); Moore (1959); Johnson (1959; 1967; 1970); Johnson et al. (1995); Ramsbottom (1973; 1977); Frost and Holliday (1980); Leeder and Strudwick (1987). Mechanisms may include eustatic sea-level changes, compaction, subsidence, and interplay of sedimentary processes operating in deltaic and fluviatile environments.

This pattern of sedimentation continued throughout Namurian times, though the periodic marine incursions became progressively less frequent and of shorter duration than in the Dinantian. The Stainmore Group is distinguished by a significantly greater proportion of nonmarine sedimentary rocks than in the Liddesdale Group. Limestones are less numerous, thinner and less pure. Seatearths and coal seams are more numerous. Several of the Stainmore Group sandstones have erosive bases that locally appear to cut out parts of the sequence. These ‘wash outs’ have been interpreted as the infillings of delta distributary channels (Moore, 1959; Leeder, 1974; Elliot, 1975). A number of separate coarse-grained, locally pebbly sandstones occupy major fluvial channel systems supplied mainly from the north-east, the courses of which may have been determined by contemporaneous fault movement.

It seems that throughout much of Dinantian and Namurian times rates of clastic sedimentation were more or less in equilibrium with rates of subsidence. It is also worth noting that, although there are striking differences in thickness between comparable sequences in block and basin areas, individual limestones, which may be correlated from one area to another, maintain approximately constant thicknesses. The great increase in thickness of sediment in the basins is generally the result of an increased proportion of clastic sediment.

By the end of Namurian times the overall depositional environment had changed to that of an upper delta plain. At this time the district formed part of the Pennine Province of cyclical Coal Measures deposition (Calver, 1969). Forest swamps, which developed widely on the emergent delta surface, gave rise to the accumulation of thick deposits of peat, seen today as coal seams. Progressive subsidence resulted in the periodic submergence of the swamps, the creation of lakes and the burial of the peat by mud, silt and sand. Delta distributary channels locally cut through previously deposited sediment forming sandstone ‘wash outs’ where coal seams have been removed. This cycle of events was repeated many times. Marine incursions were now much less frequent and are represented not by limestones but by mudstones characterised by a marine or brackish fauna. The Quarterburn Marine Band, the local equivalent of the Subcrenatum Marine Band, marks the base of the Coal Measures.

Further extensional movements, related to parts of the Iapetus Suture zone, in late Carboniferous to early Permian times led to the widespread intrusion of tholeiitic dolerite of the Whin Sill. Outcrops of this major suite of intrusions, the original sill of geological science, are confined mainly to the extreme north-west of the district although the Whin Sill is almost certainly present at depth beneath much of the district. Apart from slight flexuring and faulting of the Carboniferous rocks and the Whin Sill in post-Permian times there are no deposits or structures to record the district’s geological history until the early part of the Palaeogene. At this time widespread tensional stresses related to the major volcanic provinces in the Hebrides caused fracturing and the intrusion of tholeiitic dykes across much of northern Britain, including parts of the Northumberland Coalfield lying within the Morpeth district. The geological record remains uncertain until the onset of the widespread Quaternary glaciation. During this time, Northumberland was buried beneath a thick mantle of ice. Much of the district appears to have been affected by eastsouth-east-moving ice originating in southern Scotland and Cumbria. Nearer to the coast, ice seems to have swept southwards across the district from the Cheviots.

Chapter 2 Concealed geology

In addition to the information obtained from boreholes and mine records (see Information sources), insights into the concealed geology of the Morpeth district are provided by the results of geophysical surveys. The structure of the Carboniferous sequence at depth has been resolved by a network of seismic reflection traverses, with complementary information provided by regional gravity data. Magnetic surveys have helped resolve the pattern of Permo-Carboniferous and Palaeogene igneous intrusions.

Deep structure

Outcrop and borehole evidence from elsewhere in northern England and southern Scotland suggests that the Carboniferous strata exposed in the Morpeth district most probably rest on a basement composed of Lower Palaeozoic sedimentary rocks which were deformed and metamorphosed during the Caledonian orogeny. However, Bott et al. (1985) interpreted the results from a long seismic refraction profile, which crosses the north-western corner of the district, as indicating that any Lower Palaeozoic rocks are underlain by a high velocity, crystalline, pre-Caledonian basement at a relatively shallow (about 4000 m) depth. There is a fundamental basement boundary beneath the district; this is the Iapetus Suture, which marks the broadly north-east-trending Caledonian collisional boundary between terranes from the northern (Laurentian) side of the ancient Iapetus Ocean and those originating from its southern (Avalonian) side (McKerrow and Soper, 1989 and references therein). North-dipping lower crustal reflections on the NEC deep seismic reflection profile, which lies about 40 km to the east in the offshore area, were interpreted by Freeman et al. (1988) as the geophysical signature of the Iapetus Suture. Although the interpretation of the data provided by Soper et al. (1992) differs in detail, it is interesting to note that in both versions the inferred deep crustal suture projects towards the basement surface in the vicinity of the Morpeth district. It is likely that the broad form of the Northumberland Trough (and in particular its faulted southern margin) is to some degree ‘inherited’ as a result of reactivation of the Iapetus Suture and associated thrusts (Chadwick and Holliday, 1991).

Carboniferous basin geometry

Chadwick et al. (1993; 1995) have developed models for the structure and evolution of the Carboniferous rocks of the Northumberland-Solway region, using the results of commercial seismic reflection surveys. A major sedimentary thickening occurs across the Stublick-Ninety Fathom Fault System, between the relatively uplifted Alston Block to the south and the Northumberland-Solway Basin to the north. In the south-eastern corner of the Morpeth district there is a deepening of the Caledonian basement from about 2000 m to almost 5000 m across the basin margin faults (Figure 3). The importance of the basin margin structures is not evident from the Upper Carboniferous outcrop pattern but is reflected in a strong gravity gradient across the Ninety Fathom Fault (see inset gravity map on the geological 1:50 000 Series Sheet 14). Gravity data also indicate the presence of a cupola of the Weardale granite to the south of the district which is likely to have played a role in maintaining the rigidity and relative buoyancy of the Alston Block (Evans et al., 1988; Kimbell et al., 1989). Analysis of seismic reflection data indicates that a large part of the thickness variation in the Carboniferous sequence across the basin margin is the result of syn-depositional fault movement. Evidence from a seismic reflection profile extending southwards from Eachwick [NZ 110 710] suggests that, in the area where there is overlap between the Stublick and Ninety Fathom faults, early movements occurred on the Stublick Fault whereas the Ninety Fathom Fault was the focus for later movements (Kimbell et al., 1989; see also Chadwick et al., 1995, fig. 10). There is some evidence of syndepositional faulting later in the Dinantian, but the ‘sag’ or thermal relaxation phase of subsidence which increasingly overprints this is regional in nature rather than fault-related (Chadwick et al., 1993; 1995). A local maximum in the preserved thickness of the Stainmore Group has been identified beneath the north-eastern corner of the district and coincides with a Bouguer gravity anomaly low. The seismic data show evidence of later compressional structures (for example reverse movements on the basin margin faults) which probably relate to the effects of the Variscan orogeny (Chadwick et al., 1993; 1995).

Magnetic signatures of intrusive rocks

The Permo-Carboniferous and Palaeogene igneous intrusions within the district have a significantly higher magnetisation than the rocks they intrude, and give rise to distinct magnetic anomalies. The anomaly pattern can be resolved to a limited extent by the regional magnetic survey data (contoured in the inset map on 1:50 000 Sheet 14), but high resolution survey data from the western part of the district (Evans and Cornwell, 1981) provide a much clearer image of the pattern of igneous intrusion (Figure 4). Both Permo- Carboniferous and Palaeogene intrusions typically have significant remnant (permanent) magnetisation, which is in a different direction to that induced by the Earth’s present field. The total magnetisation of a given body will depend on the relative strengths and directions of the remnant and induced components and on any tilting the unit has undergone following the acquisition of the remnant magnetisation (Evans and Cornwell, 1981). In general terms, the anomalies due to Tertiary dykes in this district typically trend east-south-east and are ‘reversed’ (have a strong negative component), whereas dykes of Permo-Carboniferous age generally trend north-east and have a positive anomaly; structures affecting the Whin Sill have a variety of responses depending on their geometry.

The western limit of the south-east-dipping Whin Sill is marked by a pronounced magnetic anomaly in the northwest corner of the district (W in (Figure 4)). Immediately to the east of this margin are anomalies relating to the subcrop of a second (upper) leaf of the sill. The anomaly pattern here is complex, but can be interpreted in terms of the influence of a set of mainly north-east-trending faults on the component leaves of the sill. Crosscutting this part of the district is a negative eastward-trending magnetic feature (T1 in (Figure 4)) which is interpreted as the magnetic signature of a Tertiary dyke. There is an apparent offset between the western and eastern parts of the dyke anomaly resolved by the detailed airborne survey, suggesting an en echelon arrangement. Farther south, a pair of Tertiary dykes is indicated by anomalies T2 and T3 (Figure 4); there is some evidence of a slight offset in these features where they cross the intersection of apparent fault related anomalies F1 and F2 (Figure 4). Farther south, further Palaeogene dykes are indicated by anomalies T4 and T5 (Figure 4). T5 coincides with the Bingfield Dyke, which intrudes the Barrasford Fault; it is likely that, in addition to the reversely magnetised dyke, this relatively broad anomaly includes effects due to the offset and/or alteration of the Whin Sill at the fault zone.

The presence of a Permo-Carboniferous dyke is suggested by the north-east-trending positive magnetic anomaly P1 ((Figure 4); Evans and Cornwell, 1981). Farther to the south there is a distinct anomaly over the similarly trending Bavington Dyke/Hallington Reservoir Fault (P2 in (Figure 4)). The latter takes the form of a relatively broad magnetic low with a shorter wavelength magnetic high superimposed along its axis. The probable explanation is that the low is due to the offset and/or alteration of the Whin Sill at depth at the fault zone whereas the high is due to the Permo-Carboniferous dyke intruded along the same line. The airborne survey data indicate a general southward increase in magnetic anomaly level across the Hallington Reservoir Fault, suggesting that there may be a greater total sill thickness on the southern side of the fault. Ground traverses have been used to trace anomalies P1 and P2 (Figure 4) to the east of the area of detailed aeromagnetic survey (A S D Walker, unpublished data).

The St Oswald’s Chapel Dyke is the cause of a distinct short-wavelength magnetic anomaly in the Haydon Bridge area (Evans and Cornwell, 1981) which can be traced north-eastwards as far as the Barrasford Fault. To the north-east of this fault, a less distinct magnetic feature (P3 in (Figure 4)), indicative of structures at greater depth, can be traced along the projection of the dyke for about 5 km.

An unusual magnetic feature (M in (Figure 4)) is centred about 1.5 km north-west of Matfen [NZ 030 718]. It takes the form of a central annular relative magnetic high surrounded by a distinct magnetic low. When imaging methods are applied, the pattern of magnetic anomalies appears circular; however, this may be an artefact resulting from the intersection of a number of linear features combined with lack of resolution of its south-eastern edge because of a lack of detailed data. The southern edge of the feature lies along the Barrasford Fault (see above). Bateson et al. (1985) investigated the magnetic low along its western edge and concluded that it was likely to be due to faulting of the Whin Sill at depths of 300-400 m; they noted that this anomaly lies along the trend of the Fallowfield Vein, which has been worked several kilometres to the south-west, although the vein itself is not associated with an equivalent magnetic anomaly. Although a circumstantial intersection of linear features appears the most likely explanation for the Matfen anomaly, alternative explanations cannot be ruled out entirely. One interesting possibility, suggested by the apparent circularity of the feature, is that it is due to disruption of the Whin Sill as the result of a small meteorite impact. A commercial seismic reflection section recorded locally does show evidence of disruption in shallow seismic reflectors that might be expected with an impact structure, although such data degradation can be caused by other effects, for example by superficial material with poor seismic transmission qualities.

It is clear from (Figure 4) that the regional aeromagnetic data cannot resolve the fine detail of the magnetic anomaly pattern. Nonetheless these data do give some indication of the eastward continuity of features resolved by the detailed survey (see inset magnetic map on 1:50 000 Sheet 14). In particular, anomalies relating to the extensions of T2/3, T4 and T5 can be traced across the district. A pronounced negative feature which lies along the trend of T4 near Darras Hall [NZ 150 710] may be due to man-made structures, although a local thickening of the Palaeogene intrusions in this area remains a possibility.

Chapter 3 Carboniferous rocks

Introduction

The Carboniferous rocks of Northumberland, especially the economically valuable Coal Measures, have long been the subject of research. Excellent summaries of this work and of the evolution of schemes for classification of these rocks are to be found in Lebour (1876; 1886), Taylor et al. (1971), Robson (1980), Frost and Holliday (1980), Chadwick et al. (1995); and Johnson (1995).

The classification of Carboniferous rocks in the Morpeth district, used in this account, is summarised in (Table 2), where it is compared with the previous classification used in adjoining districts (Frost and Holliday, 1980; Mills and Holliday, 1998). The Carboniferous succession of north-east England may be viewed as a more or less cyclical sequence in which marine limestones become progressively thinner and less frequent as predominantly nonmarine clastic sediments become more dominant. The Liddesdale Group, of which only the upper part crops out in the district, comprises a cyclothemic sequence of mudstones, sandstones, marine limestones and some thin coals. Limestones typically comprise substantial parts of each cyclothem. The Great Limestone is one of the thickest and most easily recognised limestones in this part of the sequence, however, above it, other limestones become significantly thinner and less frequent. On the previous edition of the Morpeth Sheet, the Great Limestone was regarded as the uppermost unit of the Middle Limestone Group. More recently, Burgess and Holliday (1979), Frost and Holliday (1980) and Mills and Holliday (1998) regard the Great Limestone as the basal unit of the overlying Stainmore Group. In this sheet description the top of the Liddesdale Group is taken at the top of the Great Limestone.

Palaeontological studies of the upper part of the Liddesdale Group in the Morpeth district tend to substantiate a Brigantian (Dinantian or Lower Carboniferous) age for the Three Yard and Four Fathom limestones, and a probable lower Pendleian (Silesian or Upper Carboniferous) age for the Great limestone (Dean and Brand, 1998; Riley, 1998).

The overlying Stainmore Group (Frost and Holliday, 1980; Mills and Holliday, 1998) is entirely of Namurian age and encompasses much of the Upper Limestone Group and the whole of the Millstone Grit of previous classifications. Young and Lawrence (1998) proposed the name Morpeth Group for the strata between the top of the Great Limestone and the Quarterburn Marine Band at the base of the Coal Measures. However, on the basis of recent reviews of Carboniferous lithostratigraphical nomenclature, the name Stainmore Group is preferred.

A re-evaluation of all available palaeontological material held by the British Geological Survey, from outcrops and boreholes within the district, has indicated the presence of several Namurian stages. (Dean and Brand, 1998; Brand, 1987; Riley, 1998).

Strata above the Quarterburn Marine Band comprise the Lower and Middle Coal Measures. Rocks of the Upper Coal Measures are confined to a very small area in the south-east of the district.

Liddesdale Group

The upper part of the Liddesdale Group is represented by just over 200 m of strata that crop out in a comparatively narrow belt of country in the extreme west of the district and dip gently eastwards beneath later Carboniferous rocks. Exposure, particularly of the limestones, is generally good. A generalised succession is shown in (Figure 5).

Previous accounts of these rocks in the Morpeth and adjoining districts include those by Boyd (1861), Lebour (1875a, b, c; 1876; 1889); Smith (1912); Fowler (1936); Johnson (1958; 1959; 1995); Holliday et al., 1975; George et al., 1976; Frost and Holliday, (1980); Dunham (1990); Mills and Holliday (1998).

Detailed descriptions of the lithostratigraphy of the Liddesdale Group succession within the district, together with details of outcrop data, are given by Young (1998). Detailed reviews of the palaeontology of these rocks have been made by Dean and Brand (1998) and Riley (1998a, b). Only the essential features of the succession are summarised here, drawing attention, where appropriate, to some of the most significant parts of the sequence.

Lithostratigraphy

The Liddesdale Group comprises a succession of typical ‘Yoredale’ cyclothems characterised by the repetition of beds of limestone, mudstone, sandstone and, locally, thin coals.

Most of the limestones are laterally persistent over many kilometres and reliable correlations may be made with the equivalent limestones throughout the Northumberland Trough and the Alston Block, to the south (Holliday et al., 1975). Many lithological and palaeontological characteristics are also persistent and detailed descriptions of individual beds and cycles may be found in Frost and Holliday (1980) and Young (1998).

Liddesdale Group limestones are mainly less than 5 m thick though the Great Limestone, included here within the group, is up to 16 m thick. Typically, these limestones are medium to dark grey, coarse-grained biomicrites and biosparites in which shell and crinoidal debris is generally common. The limestones are commonly markedly bituminous. Most of the limestones are well bedded with thin mudstone or calcareous mudstone partings conspicuous, especially in weathered faces. Dolomitisation may be present locally, especially in the lower part of the Eelwell Limestone (Frost and Holliday, 1980). Iron is present in the calcite of the Redhouse Burn and Three Yard limestones. A rather irregular ‘wavy’ bedding is characteristic of the Great Limestone. Where drift cover is thin or absent the limestones commonly give rise to low scarp features with limestone brash locally abundant in the soil.

Macrofossils including brachiopods, bivalves and corals are locally conspicuous, especially on weathered faces. Microfossils include algae, foraminifera, ostracods and conodonts. A distinctive feature of the Four Fathom Limestone is the abundance, especially near the base, of beds rich in the alga Saccamminopsis fusulinaformis. The biostratigraphy of the Liddesdale Group limestones is considered briefly below, and in more detail by Dean and Brand (1998) and Riley (1998a, b).

The Great Limestone has a more or less consistent thickness of about 15 m and is the thickest limestone within the group in the Morpeth district. It is the most widely exposed, forming an almost unbroken outcrop in the western part of the district. It has been the subject of more investigation than most Dinantian limestones, for example Johnson (1958; 1959; 1995), Johnson et al. (1962), Fairbairn (1978), Frost and Holliday (1980), Dunham (1990). This is due largely to its economic importance both as a source of limestone and, in the Alston Block, to it being a major host rock for mineral veins. Many of the observations made on the Great Limestone in these surrounding areas apply equally to the Morpeth district.

Mootlaw Quarry [NZ 020 757], north of Matfen provides extensive sections through the entire thickness of the Great Limestone. Creany et al. (1980), and more recently studies by Dean during the course of this survey, showed that the major part of the limestone sequence may be divided into two almost equal portions. The uppermost portion, approximately 8.4 m thick referred to as the ‘Tumbler Beds’, a term believed to originate in the lead mines of the Alston Block where these beds were notoriously unstable, consists of relatively thick beds or posts of limestone up to about 1.0 m thick interbedded with calcareous shale beds of similar thickness. These are underlain by grey, wavy-bedded, fine-grained limestones in which shale partings are either absent or very thin and inconspicuous. These beds, collectively termed the ‘Main Posts’ are approximately 6.5 m thick. A prominent shale parting about 0.2 m thick at the base of the Main Posts may correlate with the bed of fossiliferous shale recorded by Johnson (1958) at this level in the Great Limestone exposed at Brunton Bank Quarry [NZ NY 928 570], near Chollerford in the adjoining Bellingham district. In this section Johnson described a limestone bed, approximately 1.0 m thick, beneath this shale, distinguished by the abundance of the sclerosponge Chaetetes depressus. Whereas the lowest limestone bed at Mootlaw almost certainly correlates with Johnson’s Chaetetes Band, this fossil has not been identified here.

A conspicuous feature of the Great Limestone exposed in Mootlaw Quarry, and elsewhere in the Morpeth and adjoining districts, is the presence of small, usually anticlinal, folds, known locally as ‘rolls’ (Lebour, 1875b; Frost and Holliday, 1980). These folds typically exhibit amplitudes and wavelengths of only a few metres. In well-exposed situations, such as Mootlaw Quarry, the length of the folds, measured along the fold axes, is usually of the order of a few tens of metres. Exposures in Mootlaw Quarry, observed during the course of the present survey, showed that these folds typically occur as a series of en echelon periclines. The orientation of the folds at Mootlaw, and elsewhere in the district, typically varies from north-south to north-east-south-west. In recent years the faces of Mootlaw Quarry have provided numerous fine examples of these folds. A number of generally symmetrical folds have been cut in the northern face of the workings [NZ 0144 7611] to [NZ 0190 7636]. Folding is here apparent in the top surface of the underlying sandstone, though the depth to which this affects the sandstone cannot be determined. The eastern face of Mootlaw Quarry [NZ 0224 7544] formerly provided a spectacular section through a more or less symmetrical synclinal fold, with an amplitude of several metres, which affects the whole thickness of Great Limestone (Plate 1). The underlying sandstone was not exposed at this point. The overlying mudstones were virtually unaffected by the fold. Only the lowest metre or so of these beds exhibited a slight bending into the fold; the main sequence of mudstones here were undisturbed.

Shiells (1964) described a variety of such folds in the Great Limestone and other limestones throughout Northumberland. In his descriptions he comments that the folding generally appears to be confined to the limestones with the folding usually much less intense in the underlying and overlying beds. In some instances he described reverse shears both in the folds and the associated beds. Small examples of such shears, in the form of low-angle reverse faults, which affect less than 1.0 m of limestone, have been observed locally in the northern part of Mootlaw Quarry. Shiells (1964) regarded these structures as minor folds developed at right angles to the direction of major stress during Hercynian deformation. The evidence provided by the synclinal fold in the east face of Mootlaw Quarry invites speculation on the timing of at least some of this deformation. Although inaccessible at the time of survey the junction between the folded limestone and generally undeformed overlying shale gave little indication of any slippage or plane of décollement. This structure may give evidence of a minor phase of movement during early Namurian times, perhaps related to contemporaneous fault movement.

The clastic sediments interbedded with the limestones, and usually forming the major portion of each Yoredale cyclothem, typically comprise coarsening-upwards cycles from mudstone to sandstone. Calcareous mudstones, found immediately above some limestones, typically pass upwards into mudstones with plant debris and ironstone nodules. These pass upwards, by intercalation into interbedded siltstone and sandstone, flaggy sandstone and eventually into massive, cross-bedded slightly feldspathic sandstone. Cross-bedding directions normally indicate derivation from the north. Some sandstones clearly occupy erosive, wash-out channels. Studies of heavy mineral suites from Liddesdale Group sandstones, reveal abundant zircon, tourmaline, rutile and garnet (Hemmingway and Tamar-Agha, 1975, Frost and Holliday, 1980). The tops of some sandstones commonly take the form of seatearths, penetrated by carbonaceous rootlet traces and, when particularly siliceous, comprise beds of ganister. Thin coals occur above these seatearths at several positions, though they are typically laterally impersistent and have only locally proved to be workable on a very small scale.

The thickest and most persistent coal within the Liddesdale Group of the district is the Townhead Coal, which lies almost immediately beneath the Great Limestone. This coal and its sandstone seatearth are well developed in the south-west of the district where it has been worked. The coal, generally about 0.15 m thick, is well exposed in the workings of Mootlaw Quarry where it is usually overlain by a few centimetres of mudstone rich in pyritised brachiopods and bivalves.

Biostratigraphy

The locality details of old specimens obtained from beds stratigraphically below the Three Yard Limestone are generally very imprecise and have not been re-examined in detail during this re-survey. It is therefore not possible to comment on the previous biostratigraphical range of these beds within the district.

The Three Yard and Four Fathom limestones have yielded faunas indicative of the Brigantian (P2) Goniatite Zone (Frost and Holliday, 1980) and the Lochriea mononodosa Conodont Zone (Armstrong and Purnell, 1987).

A large and varied fossil assemblage including brachiopods, bivalves, corals, crinoids and goniatites from the Great Limestone has been described by Dean and Brand (1998) and Riley (1998a, b) indicating a lower Pendleian age for this unit.

Stainmore Group

The Stainmore Group crops out in the western two thirds of the district and dips gently beneath the Coal Measures. However, the crop is mostly drift covered and consequently exposure is poor. There are numerous prominent sandstone crags and a few small stream sections, along with several long-abandoned quarries that still provide sections in some of the limestones and sandstones. A number of boreholes and the records of abandoned coal workings are also available, including the borehole at Throckley [NZ 1456 6762] which provides the most complete standard sequence for the Namurian rocks of Northumberland (Richardson, 1965; 1966; Hull, 1968; Ramsbottom et al., 1978). The overall succession in the Stainmore Group is summarised in (Figure 6). The maximum thickness is approximately 500 m, but there are local variations, especially where channel-fill sandstones are present.

Previous descriptions and interpretations of the succession now known as the Stainmore Group, in the Morpeth and adjoining districts, were given by Lebour (1875a, b; 1885; 1889); Smith (1912; 1923); Hedley and Waite (1929); Hedley (1931); Fowler (1936); Johnson (1959); Johnson et al. (1962; 1995); Frost and Holliday (1980); Lawrence and Jackson (1986); Dunham (1990) and Mills and Holliday (1998).

The Stainmore Group in its type area is a thick basinal succession in which the clastic component of cyclothems is dominated by mudstone or siltstone (Burgess and Holliday, 1979). Detailed descriptions of the lithostratigraphy of the Group, under the originally proposed name of Morpeth Group, together with outcrop data, are given by Young and Lawrence (1998). Reviews of the palaeontology of these rocks have been made by Dean and Brand (1998) and Riley (1998a, b).

Lithostratigraphy

The Stainmore Group comprises a cyclical succession of thin limestones, mudstones, siltstones, sandstones and some thin coals. These cyclothems resemble those of the Liddesdale Group, but there are differences in relative thicknesses of individual lithologies. Within the Stainmore Group, limestones are generally thinner and comprise a smaller proportion of each cycle than in the Liddesdale Group. Clastic sediments, particularly sandstones, typically occupy a greater proportion of each cycle, and coals are rather more common and laterally persistent. The main lithologies of the Stainmore Group closely resemble those of the Liddesdale Group.

Limestones, which form a relatively small proportion of the Stainmore Group, are important stratigraphical markers and many can be correlated with adjoining districts. Most of the limestones are less than 5 m thick and are today generally poorly exposed except in a few abandoned quarries. Like the limestones of the Liddesdale Group, those within the Stainmore Group are typically medium grey biomicrites and biosparites in which scattered shell and crinoid fragments may be seen locally, especially on weathered surfaces. Stainmore Group limestones appear to contain a rather greater proportion of clay and silt than those of the Liddesdale Group. Brown earthy weathering is common. Reasonable exposures of the Little Limestone may be seen in the Ingoe area [NZ 0365 7540] to [NZ 0336 7478] and in the bed of the River Wansbeck south of Wallington Hall [NZ 0307 8362]. The Corbridge Limestone, almost certainly the equivalent of the Lower Felltop Limestone of the Alston Block (Mills and Holliday, 1998), has been extensively dug in shallow quarries in the Black Heddon [NZ 073 764], Heugh [NZ 082 736] and Stamfordham [NZ 076 713] areas. The Thornbrough Limestone, equivalent to the Upper Felltop Limestone of the Alston Block (Mills and Holliday, 1998) is exposed in old quarries at Robsheugh [NZ 0980 7432] and Richmond Hill, Stamfordham [NZ 0829 7085]. Good exposures of the Newton Limestone, correlated with the Grindstone Limestone of the Alston Block by Mills and Holliday (1998), may be seen in the south of the district between Cheeseburn Grange [NZ 0922 7093] and Stobs Hill [NZ 0910 7075].

Sandstones comprise a major proportion of the Stainmore Group. The majority of these are fine to medium-grained, slightly feldspathic rocks, and in most instances are indistinguishable from those of the Liddesdale Group. Most appear to have a characteristic sheet-like form and are apparently laterally extensive over several square kilometres. Some of these give rise to prominent landscape features. Examples include the sandstone, which overlies the Great Limestone at Heugh Neb [NZ 0174 8108], that which forms the crags at Ingoe [NZ 0433 7540] above the Little Limestone and the sandstone above the Belsay Dene Limestone at Harnham [NZ 0740 8050]. In the Belsay area almost the entire interval between the Corbridge and Thornbrough limestones is occupied by sandstone. In this area the Pike Hill Limestone appears to have been removed by erosion. A coarse, pebbly sandstone at Black Heddon [NZ 0768 7610] may represent part of the channel fill deposits above this erosion surface (Jones, 1996; Young and Lawrence, 1998). The sandstones of the Belsay area give rise to a series of well-marked scarp and dip features. Parts of the sandstone succession has been much worked, particularly in the group of quarries which now form the well-known quarry gardens at Belsay Hall [NZ 0840 7840] (Plate 2). In these quarries, up to 14 m of medium-grained, micaceous, slightly feldspathic sandstone is exposed in extensive vertical faces. A conspicuous feature of this sandstone is the local abundance of small (generally less than 1 cm across) nodules of pyrite which weather to conspicuous round dark brown patches. The disfiguring caused by these nodules is prominent in many local buildings constructed from this stone, perhaps most notably Belsay Hall [NZ 0882 7836] and the buildings in Belsay Village [NZ 101 787]. Oxidation of the pyrite has not weakened the stone.

The Stainmore Group of the Morpeth district is distinguished by including a small number of very much coarser grained, locally pebbly, sandstones, which clearly occupy well marked, restricted channels. These sandstones include the Rothley Grits, the Shaftoe Grits and the small outcrop of pebbly sandstone at Black Heddon [NZ 0768 7610] noted above. The craggy escarpment of Shaftoe Crags [NZ 050 822], east of Capheaton, one of the most distinctive features of the central Northumberland landscape, marks the outcrop of the Shaftoe Grits (Plate 3). The long lines of bare sandstone crags and the dry sandy heath and grassland on the dip slope contrast markedly with the surrounding generally undulating, arable landscape. Prominent, in part wind-eroded, outcrops of the sandstones between Shaftoe Grange and East Shaftoe Hall are known as the ‘Piper’s Chair’ [NZ 0513 8163] and the ‘Punch Bowl’ [NZ 0522 8163] and a huge fallen block of the sandstone at the foot of the escarpment as the ‘Tailor and his Man’ [NZ 0520 8158]. Despite the great prominence of these sandstones as topographical features it is remarkable that no attempt was made to map them during previous geological surveys of the area, and they have attracted surprisingly little research interest. Even their true stratigraphical position has been misunderstood. In a recent review, Johnson (1995) wrongly described the sandstones at Shaftoe as lying above the Little Limestone and being equivalent to the sandstones at Rothley and Ingoe.

In the steep scarp crests along the western and southern extremities of the main outcrop the sandstone is typically coarse to very coarse grained and poorly sorted with abundant coarse grains of kaolinised, or partially kaolinised, feldspar. Rounded quartz pebbles up to 15 mm across are locally common, and in places grains of pale purple garnet may be seen in hand specimen (Hawkes and Smythe, 1931). Cross-bedding is conspicuous and jointing is usually very widely spaced.

The base of the Shaftoe Grits is not exposed. However, mapping reveals that in the area around Shaftoe Grange [NZ 0497 8200] the Shaftoe Grits comprise a lower leaf separated from the main grit sequence by a few metres of medium-grained sandstone, mudstone and a thin coal (Figure 7) and (Figure 8). This lower leaf, in excess of 50 m thick, forms the crags between Shaftoe Grange and East Shaftoe Hall [NZ 0595 8175] and includes the outcrops known as ‘Piper’s Chair’ and the ‘Punch Bowl’.

The main thickness of the Shaftoe Grits, above the Shaftoe Coal, forms the line of crags, which extend northwards from Shaftoe Grange to near Middleton Bank Top [NZ 0555 8300]. Numerous exposures of these sandstones may be seen on the long dip slope which runs north-eastwards from Salters Nick [NZ 0535 8238], at Humie Dod [NZ 0635 8206] and elsewhere south of Bolam West Houses e.g. [NZ 0685 8180] and [NZ 0717 8175] and at Huckhoe [NZ 0732 8271] and south of Bickerton [NZ 0773 8344].

The top of the Shaftoe Grits is not exposed though it must lie a short distance east Bickerton and Bolam West Houses.

The Shaftoe Grit outcrop is confined to the graben between the South Middleton-Marlish Fault in the north and the Hallington Reservoir Fault in the south (Figure 7). Within this structure, the grits occupy the sequence from above the Oakwood Limestone to beneath sandstone underlying the Newton Limestone. The Belsay Dene, Corbridge and Thornbrough limestone cyclothems have been removed by erosion of the channel system now occupied by the grits. (Figure 8).

In a recent study, Jones (1996) interpreted the Shaftoe Grits as the deposits of large, low sinuosity, fluvial channel systems that flowed towards the south-west. The coarse grain size and the scale of cross-bedding indicate high-energy conditions and powerful erosion. The coal-bearing sequence above the lower leaf of the grits may record a temporary shifting of the main area channelling and of grit deposition, allowing the resumption of deposition of typical Stainmore Group sediments, preserved here as an intercalation within the thick grit sequence.

The combined sedimentological, stratigraphical and mapping evidence suggests that the Shaftoe Grits occupy a major erosive channel system the course of which was determined by penecontemporaneous movement along precursors of the north-east-south-west trending faults.

The Rothley Grits of the Rothbury district to the north appear to occupy a similar channel system to that represented by the Shaftoe Grits, though with its base above the Little Limestone (Jones, 1996; Young and Lawrence, 1998). The small area of outcrop of Rothley Grits in the Morpeth district is concealed beneath glacial deposits.

Coals are more numerous and more laterally extensive in the Stainmore Group than in the Liddesdale Group. Several of these have been worked, though generally only on a small scale and in limited areas.

The most widespread, and formerly most widely worked, of these coals is the Little Limestone Coal. In places, the seam, including dirt partings, was found to be in excess of 1 m thick. Extensive workings are recorded on mine abandonment plans in the Kirkheaton, Ingoe Moor and Great Whittington areas. Elsewhere there is evidence in the form of spoil heaps and old shafts, that the seam has been worked on a considerable scale, though plans of most of these workings are unknown. The Oakwood Coal has been worked in several places, including Shaftoe Grange [NZ 042 822], Belsay Barns [NZ 058 779] and Halton [NZ 005 688]. The Shaftoe Coal, perhaps a correlative of the Netherwitton seams of the northern part of the district and the adjoining Rothbury district, has been worked on a very small scale between Shaftoe Grange and East Shaftoe Hall [NZ 0557 8174 to 0569 8180]. A thin coal, probably less than 0.4 m thick, known as the Chapel House Coal, which lies beneath the Pikehill Limestone, has been worked around Chapel House Farm [NZ 0810 7210] to the east of Stamfordham. Numerous old shafts to the south of Bolam [NZ 098 818] mark local workings in the Newton Coal, which lies beneath the Newton Limestone. No plans have been found for any of these workings.

Biostratigraphy

The mudstones above the Great Limestone at Mootlaw Quarry, Matfen [NZ 024 750] have yielded a large fauna, which includes brachiopods, bivalves, gastropods, crinoids and goniatites. These have been listed and discussed by Dean and Brand (1998) and Riley (1998a, b). Of particular interest is the presence of Cravenoceras cf. lineolatum, which suggests the E1a goniatite zone.

Zonally significant goniatites are rare in the Namurian of the district and only from the Great Limestone and beds associated with the locally named Pisgah Hill Limestone (in the limestone group above the Dalton Limestone) are there more than single records. Direct comparison with Namurian basinal faunas is thus not possible.

Macrofaunas above the Great Limestone up to the Corbridge Limestone show little variation, although the presence of Rugosochonetes speciosus especially above the Great Limestone helps to distinguish this part of the sequence. Above the Little Limestone, the marine beds are sandier and species of Schellwienella and Serratocrista become more common. However, it is difficult to distinguish individual marine beds one from another on the basis of their contained macrofauna. The incoming of abundant latissimoid productoids and a variety of other productoid species at the Corbridge Limestone help to distinguish this bed from earlier marine beds. There are rare records of Streblopteria ornata from the Belsay Dene Limestone at Rowlands Gill in the Newcastle upon Tyne district (Sheet 20) and from both the Belsay Dene and Corbridge limestone equivalents at Boulmer in the Holy Island district (Sheet 4) (Brand, in preparation). This species ranges up to the Lyoncross Limestone (upper E₁ goniatite zone) in Scotland. In the Throckley Borehole [NZ 1456 6762], miospores indicating the E₁ goniatite zone were found up to the succeeding Pike Hill Limestone (Owens, 1972). Throughout Northumberland a major macrofaunal change takes place at the Thornborough Limestone with the incoming of an extensive marine fauna not previously recognised in Namurian strata in the region. Miospores from mudstones shortly above this bed suggest it is very close to the boundary of the E1-E₂ goniatite zones (Owens, 1972). The succeeding Newton Limestone contains an extensive coral fauna which includes species of Aulina, also recorded from south of the Alston Block (Nudds, 1977). However, this coral fauna appears confined to the southern margins of the Morpeth region. Sinuatella sinuata appears at this level but is also present in succeeding beds. The species was also recorded as a single example from the Belsay Dene Limestone in the Ouston Borehole [NZ 0794 6931]. In places the Newton Limestone is affected by roots, as in the Throckley Borehole. Where this occurs the succeeding beds contain no distinctive faunas, although Koninckopecten scotica is present. This species ranges from the beds above the Calmy Limestone (E2a goniatite zone) up to the No. 3 Marine Band (H2-R1 goniatite zones) in Scotland. In the Throckley Borehole, these beds contain floras suggesting the E₂ goniatite zone (Owens, 1972). Elsewhere, as in the Morpeth Water Bore [NZ 1874 8800] in the Rothbury district (Sheet 9), the Eachwick Red House Water Bore 1933 and the Kyloe House Bore 1944 [NZ 1068 7037], beds containing Curvirimula sp. occur amongst marine faunas between the Newton and Dalton limestones. These beds are also present in the RAF Tranwell Borehole. The association of Curvirimula sp. and Koninckopecten sp. is typical of the Plean limestones in Scotland, which on miospore evidence are the E₂ goniatite zone (Owens et al., 1977). The faunas contained in the Dalton Limestone are poorly known; the limestone beds above this level but below the marine bands associated with the locally named Pisgah Hill Limestone are also poorly known, but do contain Posidonia corrugata suggesting the upper part of the E₂ goniatite zone. The marine beds associated with the Pisgah Hill Limestone contain rare examples of Homoceratoides sp. and these are associated with Rugosochonetes hindi. This chonetoid is found elsewhere in the Whitehouse Limestone of the Barnard Castle area (Sheet 32), the Burnfoot Shales of the Brampton district (Sheet 18) (Brand, 1991) and the Diptonfoot Shell Bed of the Newcastle upon Tyne district (Brand, personal communication). Marine bands above this stratigraphical level contain sparse faunas in which Linoproductus sp. and Productus carbonarius are present. There are no recorded goniatites to recognise the basal Westphalian marine bands, although the bed correlated with the Quarterburn Marine Band of Durham has been accepted as the most likely correlative of the Subcrenatum Marine Band (Mills and Hull, 1968). In the Throckley Borehole, miospores from this bed supported a basal Westphalian age (Owens, 1972).

Distinctive elements in the Namurian marine macrofaunas of Northumberland are shown in (Table 3). Although this table is based on a number of examined sections it represents an attempt to list some of the distinctive elements in the Namurian faunas of Northumberland where these enable isolated crops of limestones to be recognised from good collections. In Northumberland the faunas did not remain uniform over the whole basin. However, in the Morpeth district the differences are slight, and the table is intended to aid in the recognition of certain beds. Another factor affecting the recognition of individual beds is the presence of a number of disconformities, which appear to affect similar parts of the sequence to those in the Scottish Namurian. The most notable of these are in the beds above the Newton Limestone (E2a3) and those in the lower part of the more sandy developments above the Dalton Limestone (E2b? goniatite zone). The latter results in beds of H-R age resting close to the Newton Limestone equivalent in the Rowlands Gill Borehole [NZ 1664 5815] (Sheet 20) for example, and close to beds described as the E_2b goniatite zone in the Throckley Borehole. It is, however, probable that the thickest sequences of strata of Namurian age in the Northumberland basin lie within the area of Sheet 14.

Coal Measures

Within the district there are about 380 m of Lower, Middle and Upper Coal Measures resting conformably on older Namurian strata. Strata between the base of the Coal Measures and the Brockwell seam are characterised by the presence of widespread thick sandstones, but higher in the succession, apart from contained fossils, there is little to distinguish one part of the sequence from another. The thickest coals, consistently over 1 m thick, are confined to the Middle Coal Measures, but seams from the Saltwick to the Ryhope Five-Quarter are known from plans to have been mined within the district.

Lithostratigraphy

The Coal Measures, like the underlying Stainmore Group, is a cyclothemic succession. Typical cyclothems consist of the following lithologies in upward succession: mudstone (which may be fossiliferous at the base), siltstone and sandstone, sandstone, seatearth and coal. The coals, which are generally bituminous, may split into two or more seams or die out, but the major named seams are generally laterally persistent throughout the district. With the exception of one or two thick sheet sandstones, the other lithological units are impersistent. Many cyclothems are incomplete owing to their deposition in deltaic, lacustrine and semi-terrestrial environments where local rather than regional factors determined lithologies.

Mudstones are grey, darker above coals, but lighter higher in the cyclothem. They are generally silty, slightly micaceous and thinly bedded. Marine mudstones are dark grey, very silty and micaceous with large mica flakes. Ironstone, in nodules and thin beds, is common. Dominant clay minerals are illite and kaolinite.

Sandstones are feldspathic with dominant quartz and subordinate feldspar. Kaolinite, quartz and chlorite are the dominant cements. Two different geometric forms can be recognised in the sandstones. Sheet sandstones are generally less than 5 m thick, are fine to medium grained, thinly bedded, with cross-bedding and with interbedded siltstone and mudstone at top and base. Channel sandstones may be up to 30 m thick, massively cross-bedded with a meandering ribbon shape in plan and with limited lateral extent. Their thickness is very variable. Their bases are generally erosive and in places they cut down through the underlying coals forming washouts in the seams. The two geometrical forms are not mutually exclusive and many are composite.

Seatearths resemble other Coal Measures mudstones mineralogically with kaolinite and illite as the dominant clay minerals, but they show a complete lack of bedding and usually contain numerous plant roots. They have an irregular fracture along curved, near vertical, polished listric surfaces. Ironstone nodules are common and sphaerosiderite is present locally.

Biostratigraphy

Dean and Brand (1998) have undertaken a review of British Geological Survey holdings of fossils from the Coal Measures rocks of the district. The faunas are listed in (Table 4) and (Table 5).

Nomenclature and classification

The evolution of seam correlation in the Northumberland and Durham coalfields is well described by Land (1974, p. 15). The coal seam names used are based largely on the standard Northumberland county series, local names and the correlation with the British Coal county seam index letters is shown in (Table 6).

The base of the Lower Coal Measures is taken at the base of the Subcrenatum Marine Band, and that of the Middle Coal Measures at the base of the Vanderbeckei (Harvey) Marine Band. The base of the Upper Coal Measures is taken at the base of the Cambriense (Down Hill) Marine Band. The Langsettian (Westphalian A) Stage is coincident with the Lower Coal Measures. The Duckmantian (Westphalian B) Stage equates with the lower two-thirds of the Middle Coal Measures up to the base of the Aegiranum (Ryhope) Marine Band. The Bolsovian (Westphalian C) Stage includes the upper third of the Middle Coal Measures and the basal part of the Upper Coal Measures exposed within the district. The Coal Measures are further subdivided using nonmarine bivalve zones.

Lower Coal Measures

The Lower Coal Measures forms an outcrop up to 4.4 km wide. Strata up to the Marshall Green coals consist largely of sandstone, with three impersistent thin coals the Saltwick, Gubeon and Ganister Clay coals. Thin dark grey mudstones occur within this part of the sequence, including the equivalent of the Amaliae (Gubeon) Marine Band about 10 m above the Saltwick Coal. The Saltwick Coal was mined on a very small scale in the north of the district, but the Marshall Green is the lowest coal to have been extensively worked. The Marshall Green, commonly split into Top and Bottom leaves, averages 50 cm in thickness, locally exceeding 1 m. It is a clean bright coal usually of high quality. The impersistent thin Stobswood Coal is overlain throughout much of the district by a mudstone bed with a fauna indicative of the Stobswood Marine Band. Sandstone comprises much of the sequence from the marine band to the overlying Victoria and Brockwell coals. A geographically widespread, if faunally variable, mussel band known as the Victoria Shell Bed, occurs above the Victoria Coal. The Brockwell Coal was worked throughout the district. In the south, it is a single seam of good quality, commonly 1 m thick, but splits northwards into a series of thin coals.

The thickness and quality of the Three-Quarter Coal increases north-eastwards across the district. Locally it has a relatively high chlorine content. It was worked until 1988 at Ashington Colliery. The strata between this and the overlying Busty Coal is dominated by a thick, locally coarse-grained and conglomeratic, sandstone which forms the roof of the Three-Quarter Coal.

The Busty Coal is normally split into two leaves each up to 1 m in thickness. Both the Top and Bottom Busty seams have been widely worked.

The Tilley Coal is generally split into three or four leaves spread over up to 10 m of strata; the coals are usually of inferior quality and only very small areas have been worked. The thin overlying Hodge Coal is similarly of poor quality and has not been mined in the district. Correlation of the thin coals between the Tilley and the Beaumont coals is tentative. The Beaumont Coal is a good quality coal which generally maintains a thickness of about 1 m and has been mined extensively to the south of the Stakeford Fault. Throughout much of the district the Beaumont Coal is overlain by a mudstone unit which contains a fragmental clayrock at its base (Richardson and Francis, 1971) succeeded by a distinctive shell bed containing a musselostracod fauna termed the Hopkins Band (see Land, 1974, for origin of the name). The interval up to the Vanderbeckei (Harvey) Marine Band contains a thick south-east-trending channel sandstone in the north of the district, but is variable elsewhere, commonly with two thin impersistent coals.

Middle Coal Measures

The thickest and most consistent coal seams occur in the Middle Coal Measures. The Vanderbeckei (Harvey) Marine Band, the base of which marks the base of the Middle Coal Measures, consists of up to 1 m of very dark grey to black shale containing sparse Lingula mytilloides. Overlying the marine band are mudstones with a mussel band at the base. Massive sandstone occupies much of the sequence between the marine band and the Plessey Coal. North of Brenkley an intermediate seam, the Bottom Plessey is developed and has been mined in the north-east of the district where it is up to 96 cm thick. The Plessey Coal generally consists of two thin leaves, and is commonly washed out in the south of the district, but has been wrought extensively in the north, where it is of good quality without dirt bands, averaging over 75 cm in thickness. Measures between the Plessey Coal and the Northumberland Low Main Coal are variable in lithology and contain an intermediate thin coal, the Broomhill Main Coal (Plate 4). Two fossiliferous beds occur in places above the Plessey, the upper containing a prolific fauna and referred to as the Plessey Shell Bed.

The Northumberland Low Main Coal is generally of very good quality and has been extensively worked; it exceeds 2 m in thickness locally. The overlying measures up to the Durham Low Main Coal are variable both in lithology and thickness, ranging from as little as 2 m up to 27 m and with mussel bands and thin coals developed locally.

The Durham Low Main Coal is commonly banded. In the north of the district it consists of top and bottom leaves of thicker coal, usually with intermediate thinner coals, although locally occurring as a single united seam up to 1.8 m thick. The large range in coal and inter-coal thickness variation makes correlation of individual coals difficult. Throughout most of the district the Durham Low Main Coal is overlain by a massive, cross-bedded, medium-grained sandstone, the Low Main Post, which in the south generally rests directly on the coal and provides an excellent roof for workings. The sandstone was quarried within the district.

Except to the north of the Stakeford Fault and near Killingworth, where it is a single banded seam, the overlying Bensham Coal is also split into top and bottom leaves, which have been worked separately. The mudstone overlying the Bottom Bensham Coal in the west of the district carries a mussel band, but the strata between the Bensham and the overlying Yard coal is dominated by a thick sandstone, which in places has cut down through the Bensham Coal.

North of Wolsington the Yard Coal is consistently about 1 m thick, free of dirt bands and of excellent quality, perhaps the best in the Northumberland Coal Measures. It is locally overlain by thick sandstone. The thin Bentinck Coal has been worked in the north of the district where a fossiliferous mudstone forms its roof.

Succeeding strata contain, in upward succession, the Metal, Five-Quarter and High Main coals. Their relationships are highly variable throughout the district such that in different areas they have a tendency to split or to come together. The High Main is most consistent in the south where it is a good quality coal commonly 1.5 to 2 m thick; it formed the basis of the early coal mining industry in Newcastle. The three seams converge south of Bedlington where they are represented by 6 m of coal in 12 leaves within 10 m of strata. Between Brunswick and Cramlington the interval comprises mainly sandstone.

The strata between the High Main Coal and the Maltby (High Main) Marine Band is variable. In the south of the district and near Bedlington, the High Main is itself overlain by massive sandstone, the High Main Post. North of the River Blyth, the intervening Ashington Coal is present, with a maximum thickness of 50 cm within the district. The Maltby Marine Band is overlain by a prolific mussel band.

Strata above the Maltby Marine Band are exposed only in the south-east of the district. Up to six named coals are present in the sequence up to the Haughton (Kirkby’s) Marine Band. The lowest of these, the Moorland Coal, is the thickest, locally up to 1.2 m thick, but is commonly split into two leaves; it was mined on a small scale. The overlying Ryhope series of coals are generally thin-banded seams, although the Ryhope Five-Quarter Coal was worked around Gosforth, and the thin Rowlington Coal is present only near Ashington.

The Haughton (Kirkby’s) Marine Band is characterised by an alternation of marine and nonmarine phases. The strata up to the overlying Sutton (Hylton) Marine band consist mainly of sandstone. The succeeding strata up to the Aegiranum (Ryhope Marine) Band (which forms the base of the Bolsovian) is also dominated by massive, coarse-grained and locally pebbly sandstone with the thin Burradon Coal near its base.

The Usworth Coal is up to 76 cm thick. The overlying Hebburn Fell Coal is generally split. There are several thin coals between the Hebburn Fell Coal and the position of the Cambriense (Down Hill) Marine Band (which marks the base of the Upper Coal Measures) including the West Moor and Killingworth seams.

Upper Coal Measures

The Cambriense (Down Hill) Marine Band itself has not been proved within the district, but strata above this level lie immediately north of the Ninety Fathom Dyke near Longbenton. They are among the highest Westphalian strata in Northumberland.

Chapter 4 Intrusive igneous rocks

The Carboniferous sedimentary rocks of the Morpeth district are intruded by two groups of basic igneous rocks. The older of these, with the larger area of outcrop, is the complex of quartz-dolerite intrusions known collectively as the Whin Sill, of late Carboniferous or early Permian age. Also present, are representatives of the tholeiitic dyke swarm, which radiates from the Palaeogene igneous centre on the Isle of Mull.

Whin Sill and related dykes

The Whin Sill of north-east England is the original sill of geological science. The name derives from the long established quarryman’s term, ‘whin’, for any hard black rock, combined with the north of England miners’ and quarrymens’ term, ‘sill’, which was applied to any more or less horizontal body of rock. The earliest geological interpretations of the Whin Sill regarded the sheets of dolerite as contemporaneous lava flows (Hutton, 1832; Phillips, 1836). Its true intrusive nature, which was first suggested by Sedgwick (1827) in Teesdale, was recognised by Tate (1870) and thereafter became generally accepted in the light of the primary survey of northern England (Topley and Lebour, 1877). The Whin Sill suite of intrusions has subsequently attracted a large volume of petrographical and geochemical study, for example Teall (1884a, b), Holmes and Harwood (1928), Tomkieff (1929), Smythe (1930), Randall (1959; 1980a), Harrison (1968), Dunham and Strasser-King (1982) and Dunham (1990).

The Whin Sill suite comprises a series of closely related sills, together with associated dykes. Whereas, over much of its very extensive outcrop across northern England, the Whin Sill occurs as a single sill, in places it may be separated into two, or very exceptionally more, leaves. The Whin Sill crops out only in the extreme north-west of the Morpeth district around Kirkwhelpington. From regional considerations, the sill is believed to underlie the whole of the district south-east of these outcrops. Aspects of the concealed areas of Whin Sill are discussed in Chapter 2.

The relatively small outcrops of the Whin Sill in the district are generally inconspicuous features in the landscape, in contrast to the striking, craggy topography, which characterises the more extensive sill outcrops of the Roman Wall country and the Northumberland coast.

In the Kirkwhelpington area, the Whin Sill is intruded in at least three horizons. The most extensive outcrops, north of the village and including that formerly worked in East White Hill Quarry [NY 9948 8576], and south of the village, are immediately beneath the Shotto Wood Limestone. At Knowesgate, an isolated outcrop [NY 990 860] clearly forms part of a lower leaf, intruded between the Upper Bath-House Wood and Eelwell limestones. Between Kirkwhelpington and Cambo [NZ 026 857], three leaves are present locally: between the Shotto Wood and Eelwell limestone; immediately beneath the Four Fathom Limestone; and at variable levels between the Four Fathom and Great limestones. On the south bank of the River Wansbeck [NZ 0022 8445], near Ivy Crag, a small knoll-like intrusion of Whin Sill dolerite occurs within the Eelwell Limestone.

Outcrops of the Whin Sill typically show crudely developed columnar jointing, locally with dark brown spheroidal weathering of jointed blocks. These features are well seen in the faces of the abandoned East White Hill Quarry [NY 9948 8576]. In hand specimen the dolerite is typically a fine-grained, dark grey rock, without obvious phenocrysts. A thin section of this rock (E71826) shows it to be composed principally of relatively fresh plagioclase, clinopyroxene and some opaque iron oxides with fairly common interstitial pockets of micrographic quartzfeldspar intergrowths (Beddoe-Stephens, 1998).

The Throckley Borehole [NZ 1456 6762] (NZ16NW/45), in the extreme south of the district, proved the sill to be 38.5 m thick in the interval between the Great and Little limestones. In a detailed study of the Whin Sill core from this borehole, Dunham and Strasser-King (1981) noted three distinctive ‘Whin’ lithologies.

‘White Whin’, a light grey, very fine-grained, highly altered quartz dolerite, occurs as a 6.4 cm-thick zone at the top of the sill. Pyroxene and plagioclase are completely pseudomorphed by carbonate and clay-carbonate aggregates respectively. Minute pyrite grains occur scattered throughout the rock and ankerite and anatase are also present. Small amygdales (0.2 to 0.5 mm across) containing quartz rimmed by calcite occur, especially close to the margin of the sill.

‘Brown Whin’ is a term applied by these authors to an altered variety of dolerite, typically brown in thin section, found as a 11.5 cm-thick zone immediately beneath the white whin at the top of the core, and as a 15.3 cm-thick zone at the base. In this rock plagioclase is fairly fresh, though pyroxene is mostly pseudomorphed by carbonates. Amygdales containing quartz and calcite are present but are fewer and larger in size, up to 0.8 mm, than in the white whin.

The bulk of the Whin Sill in the Throckley cores consists of dark grey, fine to medium-grained dolerite in which plagioclase and pyroxenes are usually fresh. Small amounts of altered orthopyroxene occur, mainly as phenocrysts. Opaque minerals consist mainly of iron-titanium oxides. Quartz is present as discrete grains and in interstitial graphic intergrowths with alkali feldspar (micropegmatite). A few quartz-and calcite-filled amygdales, up to 1.5 mm across, occur in the upper part of the sill. Phenocrysts of plagioclase and altered pyroxene occur near the base (Dunham and Strasser-King, 1981).

Four boreholes in the Belsay and Black Heddon areas recorded Whin Sill dolerite between 1.2 and 2.3 m thick in the sequence between the Little and Oakwood limestones. No samples have been traced. The small thickness of dolerite suggests these may be part of a thin upper leaf, with the main sill present at a greater depth.

Associated with the Whin Sill of Northumberland are numerous related dykes which may be separated into four discrete dyke echelons with a general north-east to eastnorth-east trend (Randall, 1980a, b). Dykes that form part of the St Oswald’s Chapel Dyke Echelon cross the northwestern part of the Morpeth district.

Dolerite dykes are known to occupy the Hallington Reservoir Fault at several localities and it is possible that much, if not all, of this fault may be intruded by Whin Sill dolerite across the district. In the headwaters of the River Blyth, south of Cocklaw Walls, a dolerite dyke, within the Hallington Reservoir Fault, forms a prominent, low craggy outcrop adjacent to the outcrop of the Three Yard Limestone and overlying sandstone [NZ 0025 7792 to [NZ 0041 7798]. The dyke is at least 12 m wide though the walls are not exposed. The rock (E71827) and (E71828) is a sparsely microporphyritic dolerite composed mainly of plagioclase and clinopyroxene with patches of devitrified interstitial glass with dendritic iron oxides. Microphenocrysts consist of plagioclase, clinopyroxene and fine-grained aggregates of mica-chlorite, which may originally have been orthopyroxene or olivine. Very small quartz-and-calcite-filled amygdales are common near the margins of the dyke (E71827) (Beddoe-Stephens, 1998).

Small trials for lead ore have been made in the Hallington Reservoir Fault immediately south of Sandybraes, Capheaton [NZ 0318 7903]. The small amount of spoil remaining here contains a few blocks of dolerite suggesting that the fault may here be occupied by a dyke. Magnetometer surveys have confirmed this. A thin section (E71825) of a block from the spoil heap shows a microporphyritic dolerite composed of plagioclase and clinopyroxene and patchily distributed devitrified interstitial glass with skeletal iron oxides. Microphenocrysts comprising conspicuously zoned plagioclase up to 1.5 mm long are present, together with less common aggregates of fine-grained mica-chlorite which may represent original orthopyroxene or olivine (BeddoeStephens, 1998). A more altered example of this dolerite (E71824) displays complete replacement of clinopyroxene by intergrown turbid chlorite and Fe-oxyhydroxide and patchy carbonate. Feldspars show incipient alteration to while mica and primary opaque oxides are replaced by secondary ironoxide and (tentatively identified) leucoxene/rutile (BeddoeStephens, 1998).

The possible presence of dolerite within this fault south of White House, between Cocklaw Walls and Sandybraes, is suggested by thermal metamorphism of bitumen in veins in the Great Limestone in the abandoned limestone quarry [NZ 0170 7865] south of White House (Creaney et al., 1980).

Whin Sill dolerite occurs in the Hallington Reservoir Fault in the Bolam area where small pits have been excavated in the dyke south-west of Hillhead Cottages [NZ 0945 8217]. No dolerite is exposed here today though loose blocks may be seen in the soil. A thin section of this rock (E71822) shows fine-grained dolerite (typically 0.3 to mm) composed dominantly of fresh plagioclase and clinopyroxene. Equant, subhedral to anhedral opaque iron oxides are common. Traces of intergranular, partly uralitised brown hornblende also occur. Microphenocrysts comprise plagioclase and uralitised pseudomorphs possibly after orthopyroxene or olivine. Interstitial areas are commonly occupied by devitrified glassy mesostasis (Beddoe-Stephens, 1998).

Fresh dolerite, also within the Hallington Reservoir Fault, is exposed in the banks of a small stream [NZ 1079 8336] south of Pilmoor Plantation, south-west of Meldon. Although the walls are not exposed, the dyke must be at least 5 m wide. In thin section (E71823) this dolerite is seen to be a very fresh fine-grained dolerite composed of plagioclase and clinopyroxene, and disseminated subhedral to anhedral opaque oxide. Sparse microphenocrysts of plagioclase are up to 1.5 mm. Rare microphenocrysts (up to 1.5 mm across) that possibly replace olivine are altered to chloritic minerals. Interstitial glass is conspicuous and is commonly unaltered (Beddoe-Stephens, 1998).

Magnetometer surveys in the Wallington area have inferred the presence of a hitherto unsuspected basic dyke within a fault parallel to the Hallington Reservoir Fault in the Middleton Burn area [NZ 0382 8564] to [NZ 0476 8615], east of Cambo.

Contact metamorphism

Little is known of the contact metamorphic effects of the Whin Sill and its associated dykes in the Morpeth district as there are very few exposures of the country rocks close to the intrusions. The Eelwell Limestone at Ivy Crag [NZ 0022 8445], on the south bank of the River Wansbeck at Kirkwhelpington, is recrystallised to a medium-grained marble adjacent to the sill. Hydrocarbons in veins in the Great Limestone at the abandoned quarry [NZ 0170 7865] south of White House suggested thermal metamorphism (Creaney et al., 1980). Contact metamorphism is probably of limited extent and no evidence has been found for the development of the calc-silicate assemblages described by Randall (1959) and Frost and Holliday (1980) in the adjoining Bellingham district (Sheet 13).

Palaeogene dykes

A few west to west-north-west-trending basic dykes cut the Coal Measures rocks of the district. They have been quarried on a small scale locally and have been encountered in places in underground coal workings, though none is exposed today. These dykes form part of a large suite of dykes of the same general trend elsewhere in northern England, which form part of a dyke swarm emanating from the Palaeogene igneous centre of Mull in western Scotland. These intrusions have been described by Teall (1884a; 1888; 1889), Lebour (1878; 1886), Heslop and Smythe (1910), Holmes and Harwood (1929), Tomkieff (1953) and Randall (1980b). Although differences in petrography have been noted between individual dykes they are all tholeiitic dolerites. They are typically olivine-free or olivine-poor plagioclase-clinopyroxene rocks, with the feldspar and pyroxene generally exhibiting an ophitic relationship, and with an intersertal texture and glassy mesostasis, which is usually devitrified or microcrystalline. Anorthite phenocrysts may be present.

Two dyke outcrops were formerly seen at Bothal Mill [NZ 2345 8617], and in a quarry at Climbing Tree [NZ 2165 8627], east of Morpeth, where the dyke had a width of over 4 m. These outcrops may represent a westerly continuation of the West Sleekburn Dyke of the Tynemouth district (Sheet 15) to the east.

Mine plans record the presence of several en echelon dykes, in the Top Busty, Beaumont and Plessey seams east of Hepscott [NZ 223 840]. These are the westerly continuation of the Barrington-North Blyth Dyke of the Blyth area in the Tynemouth district. There is no evidence that any of these reach surface in the district.

A small quarry [NZ 2230 7886] on the north bank of the River Blyth south-east of Stannington is understood to have been worked for dolerite though nothing is exposed today. This may represent the Hartley North or Hartley South dykes of the Seaton Sluice area in the Tynemouth district.

The longest mapped outcrop of a Palaeogene dyke in the district is that of the Coley Hill Dyke [NZ 1555 6810] to [NZ 1918 6746] in the North Walbottle and Westerhope area. This dyke is recorded as reaching 23 m in width locally. It was worked in a small quarry at Whindykes [NZ 1859 6760] where the adjacent Five-Quarter Coal was burnt to coke; there is no longer any exposure.

Chapter 5 Structure

The main structural elements of the district are summarised in (Figure 10). The Carboniferous rocks exhibit a gentle regional easterly dip rarely exceeding 10°. This comparatively simple structure is interrupted by a shallow syncline in the Tranwell -Saltwick area, south of Morpeth. Lawrence and Jackson (1986) noted a series of open, minor flexures within this structure, together with a minor east-west-trending anticline marking the southern limit of the folded strata south of Bells Hill [NZ 195 789].

Folds

The presence of small-scale folds or ‘rolls’ within the Great Limestone has long been known in this and adjoining districts (Lebour, 1875b; Frost and Holliday, 1980). These folds typically exhibit amplitudes and wavelengths of only a few metres, with the length of the folds, measured along the fold axes, usually of the order of a few tens of metres. The orientation of these folds typically varies from north-south to north-east-south-west. Within the Morpeth district these structures are best seen in the working faces of Mootlaw Quarry [NZ 014 761] and in the nearby abandoned quarries at Kirkheaton [NZ 0190 7725] and Ryal [NZ 0185 7445] to [NZ 0230 7435] (Young, 1998). Exposures in Mootlaw Quarry showed that these folds occur as a series of en echelon periclines. A more or less symmetrical synclinal fold, with an amplitude of several metres was exposed in the eastern face of Mootlaw Quarry (see Liddesdale Group). Whereas this fold affected the entire thickness of the Great Limestone, the overlying mudstones were seen to be virtually unaffected by it (Plate 1).

Shiells (1964) described a variety of such folds in the Great and other limestones throughout Northumberland.

Faults

Intersecting the Carboniferous rocks is a conjugate series of faults. The predominant fault trend is east-north-east, but a number trend east-south-east, especially in the eastern part of the district. In common with similar areas elsewhere, the degree and complexity of faulting within the Coal Measures outcrop in the district almost certainly reflects the very much larger volume of data for these rocks compared with that for the outcrops of the Stainmore and Liddesdale groups.

The district is crossed, in the extreme south-east, by the east-north-east-trending Ninety Fathom Dyke. This forms part of the Ninety Fathom-Stublick Fault System that bounds the Northumberland Trough on its southern side, separating it from the structural unit of the Alston Block to the south. This fault throws down to the north. The throws estimated at up to 280 m in the Longbenton area [NZ 254 683] decreasing to approximately 200 m at the southern margin of the district. Jackson et al (1985) noted a hade of up to 45° in the Killingworth Moor area, and commented that mining records prove that the dip of adjacent strata increases to 45° on the downthrow side of the fault. The Ninety Fathom Dyke may be readily traced south-westwards across the adjoining Newcastle upon Tyne district, and eastwards to the coast across the Tynemouth district.

The district is crossed by several other faults with a predominantly east-north-east trend, parallel to that of the Stublick-Ninety Fathom Fault. Several of these may be traced from the adjoining Bellingham district on the west and also continue eastwards into the Tynemouth district.

Prominent amongst these is the Hallington Reservoir Fault, which enters the district west of Kirkheaton. Dolerite dykes, part of the Whin Sill suite, are known to occupy this fault at several places along its outcrop. It is possible that much, if not the whole of this fault may have been exploited by this intrusion. The Hallington Reservoir Fault throws down to the north and, with the parallel southerly downthrowing South Middleton-Marlish Fault, to the north, forms a graben up to 4 km wide in the area of Shaftoe Crags. Young and Lawrence (1998) suggested that the Shaftoe Grits occupy a major channel system eroded through the strata between the Oakwood and Thornbrough limestones, the course of which may have been determined by penecontemporaneous movement along precursors of the east-north-east-trending faults.

Within the Coal Measures outcrop in the east of the district Jackson et al. (1985) and Lawrence and Jackson (1986; 1990) have shown that faults generally exhibit displacements of 25 m or less. Greater displacements, of up to 70 m, are recorded for the Stakeford and Crimea faults. A plexus of faults associated with the former fracture causes significant displacement and rotation of strata within individual fault blocks north of Gubeon [NZ 1725 8330] (Lawrence and Jackson, 1985). Information available from mine plans shows that the Stakeford Fault hades north at up to 45°. As in the case of the Ninety Fathom Dyke, the dip of strata adjacent to the downthrow side of the Stakeford Fault increases locally to 45°, though beds on the up throw side are relatively undisturbed (Lawrence and Jackson, 1990).

Within the Coal Measures many faults terminate against crossfaults, whereas others die out gradually as their throw reduces or as they pass into several fractures, commonly with opposing throws.

Chapter 6 Quaternary

Quaternary (drift) deposits mantle almost the entire Morpeth district and, except in a few places mainly in the west and in some valley bottoms, largely conceal the underlying Carboniferous rocks. The unconformity that separates the solid and drift deposits in north-east England represents a very long period of geological history during which perhaps as much as 2000 m of Mesozoic strata, and some Upper Carboniferous rocks, were removed by erosion (Holliday, 1993). It is likely that the district experienced several periods of glaciation during the Pleistocene, though the deposits seen today date only from the latest (Late Devenisan, or Weichselian) glaciation. Any deposits formed during earlier glaciations have either been removed or recycled by subsequent glaciations.

The Quaternary sediments of the district include a variety of deposits formed during the advance and retreat of the Pleistocene ice sheets, together with those which have accumulated subsequently, including sediments being deposited today, mainly by fluvial processes. Till or boulder clay is the most widespread drift deposit across the district, but water-laid sands, gravels, silts and clays, formed during the glacial and the immediately post-glacial period occur locally, especially in buried valleys. Numerous boreholes in the eastern half of the district reveal that drift cover is up to 20 m thick over large areas, and this increases locally to in excess of 60 m in buried valleys. Drift cover is generally thinner in the western half of the district. Though there are few reliable borehole records in this area, the rockhead surface is betrayed by numerous generally small drift-free outcrops.

Despite the widespread occurrence of drift deposits they are typically very poorly exposed. Information on their nature is derived largely from records of boreholes and temporary sections.

Important accounts of the Quaternary of the Morpeth district and adjoining areas include those by Howse (1864), Dwerryhouse (1902), Woolacot (1905; 1921), Smythe (1908; 1912), Merrick (1910; 1915), Raistrict (1931), Peel (1949; 1956), Sissons (1958; 1960), Beaumont (1968), Cuming (1970; 1977), Francis (1970), Taylor et al. (1971), Thabet (1973), Sladen (1979), Lunn (1980), Eyles and Sladen (1981), Jackson et al. (1985) and Lawrence and Jackson (1986; 1990).

Rockhead surface

Records of numerous boreholes in the eastern part of the district enabled Lawrence and Jackson (1986; 1990) to contour the rockhead surface. It is clear from this that, in common with other glaciated lowland areas, the rockhead surface has an appreciably greater relief than the till plain which forms the present-day surface. Pre-existing, possibly pre-glacial, valleys coincident with, or marginally offset from the present-day valleys of the Wansbeck, Catraw Burn, River Blyth, and Ouse Burn are largely infilled with glacial drift. A large buried valley to the north and northeast of Ponteland runs beneath Prestwick Carr, joins the buried valley of the River Blyth near Ewe Hill [NZ 197 767] and continues northwards to join the buried valley of the Wansbeck at Hepscott [NZ 222 843] (Figure 11). These valleys are graded to a little below Ordnance Datum (OD) in the east of the district, though farther to the east in the adjoining Newbiggin district buried valleys are locally graded to more than 20 m below present-day sea level.

Glacial meltwater channels

Glacial meltwater channels, formed during de-glaciation, may be seen in several parts of the district. Whereas some of these may, at least in part, have developed along pre-existing, perhaps fault-guided, valleys, many developed in response to local topography and ice cover during deglaciation. Clark (1970) described a series of small glacial meltwater channels (up to 5.5 m wide and up to 3.5 m deep) and ‘microchannels’ (up to 0.60 m wide and up to 0.75 m deep) in the Shaftoe Grits at Shaftoe Crags [NZ 054 822].

Glacial deposits

Till, or boulder clay, is the most widespread and thickest of all the Quaternary deposits and covers more than 75 per cent of the district. It rests directly upon the underlying rocks, and in much of the district it is the main or only drift deposit present. Lawrence and Jackson (1986) recorded a thickness of 40.7 m of till within the buried valley of the proto-Ouse Burn, though thicknesses in excess of 60 m are present in the Morpeth and Stannington area (Lawrence and Jackson, 1990). Where unweathered, the till is typically a stiff, grey to greyish brown, silty, sandy or stony clay. Thin sand lenses and partings of sand, gravel, silt and clay are common throughout. Included cobbles and boulders consist chiefly of Carboniferous rocks, mainly sandstone with subordinate amounts of limestone, siltstone, mudstone, ironstone and coal. Dolerite, from the Whin Sill, is common, especially in the west of the district. More rarely a few far-travelled erratics are present. The distribution of erratics derived from southern Scotland, the Lake District and the Cheviots in the till of Northumberland has been summarised by Lunn (1980). Greywacke sandstones and granites, derived either from south-west Scotland or the Lake District are sparingly present across much of the district. Volcanic rock types derived from the Borrowdale Volcanic Group of the Lake District, are found throughout much of the south of the district. Cheviot volcanic rocks occur sparingly only in the north-eastern part of the district.

Erratics vary in size from a few millimetres to large boulders, with the latter commonly increasing in abundance towards rockhead. Exceptionally large erratics have been encountered locally. A probable glacially transported sandstone ‘raft’ of this sort within a thick till sequence occurs north of Stannington [NZ 212 802]. Boreholes and temporary sections here recorded up to 6 m of flaggy sandstone with variable dip, near the top of a drift sequence believed to be over 30 m thick. The size of this large erratic is unproved though it may well be several tens of metres across. A much larger ‘raft’, more than 270 m long, was found in the Tranwell Opencast Site [NZ 185 837] (Lawrence and Jackson, 1986). A section recorded in one working face showed:

A similar ‘raft’ was worked in the Glororum Opencast site [NZ 191 822].

The district’s largest known erratic occurs at Down Hill [NZ 005 684], east of Halton Red House. A large glacially transported raft of Great Limestone up to 600 m across here forms a prominent low hill rising above the covered outcrop of the beds above the Oakwood Limestone (Plate 5). Limestone has been worked from the erratic in Downhill Quarry on the western side of the hill. A section in the northern corner of the quarry [NZ 0046 6861] shows 3.75 m of grey brecciated limestone. It is not known whether this large raft rests directly upon solid rocks or is separated from them by till.

Identification of such large glacially rafted erratics is difficult in boreholes or in poorly exposed ground. However, in view of their relatively common occurrence in other parts of the Northumberland and Durham Coalfield (Moore, 1994), they may be more widespread in the Morpeth district than is suggested by the limited records available.

In places, the surface of the till is moulded into a series of gentle, low, drumlin-like ridges with a generally east-west alignment, parallel to the direction of ice flow during the last glacial period.

The greater part of the till which mantles the area is largely an overconsolidated lodgement till, thought to be the product of a single late-Devensian glacial episode. However, Lawrence and Jackson (1986; 1990) commented on the widespread occurrence of a distinct upper layer of till comprising mottled orange-brown and grey clay with a significantly lesser stone content. This they interpreted as an upper lodgement, ablation or flow till, a product of gelifluction or a postglacial weathering profile (Eyles and Sladen, 1981). Deposits of this type have been described as Upper Clays or Upper Stony Clays of south Northumberland by Mills and Holliday (1998). They are almost certainly equivalent to the ‘Superficial clays’, which include the Pelaw Clay and the Prismatic Clay, of the Sunderland district described by Smith (1994). Mills and Holliday (1998) have noted that in the adjoining Newcastle upon Tyne district, these Upper Clays are the weakest of the stony clays, especially in the lower part of the deposits, where they become soft and plastic when in contact with water-bearing beds; they can be very unstable in excavations. Poor exposure prevents separate mapping of these Upper Clays in the Morpeth district.

Glaciofluvial deposits consist of sand and gravel that form extensive spreads in various parts of the district. They flank the River Wansbeck and parts of the surrounding country downstream from Meldon Park [NZ 109 850]. They cover a considerable area in the Ogle [NZ 137 788] and Kirkley Hall [NZ 150 772] areas, and around Eachwick [NZ 115 711] and Fawdon [NZ 227 696]. Much smaller, isolated patches of these deposits occur scattered between these larger outcrops. The surface expression of these deposits is commonly, though not invariably, marked by rather irregular, hummocky, well-drained country. Good examples of this scenery include the areas around Eachwick, Kirkley Hall and north of Meldon [NZ 119 841]. The sand and gravel usually rests on boulder clay and a spring line is common at the base. In addition to these surface outcrops, Lawrence and Jackson (1986) noted that a number of boreholes and trial pits within the district have encountered sand and gravel, usually associated with the glacial sequence within buried valleys. The comparatively few exposures of these deposits suggest that they generally comprise fine to medium-grained sand with silty and clayey interbeds and with lenses and layers of pebble and cobble gravel up to 2 m thick. Lawrence and Jackson (1986) commented on the presence of gravel forming the base of these deposits in a number of localities. Rock types within the gravels are generally similar to those in the till. Sandstone is most abundant with smaller quantities of limestone, dolerite and some ironstone. Lawrence and Jackson (1986) noted the presence of coal fragments in the sand fraction.

Sand and gravel have been worked, mainly on a small scale, from several small pits in most of the larger outcrops. There are few good sections in these deposits available today.

Individual beds of sand and gravel within boreholes and trial pits range up to a maximum of 9.9 m west of Morpeth [NZ 1765 8561], but most commonly thicknesses do not exceed 2 m. Although detailed lateral and vertical relationships of the glacial deposits are not generally clear, borehole records indicate that sand and gravel is largely confined to the buried valleys where it occurs as thin and laterally impersistent lenses and not in single correlatable units.

As in the adjoining district (Mills and Holliday, 1998), the form and distribution of the sand and gravel deposits is consistent with deposition having taken place dominantly in a subglacial environment from seasonal streams and from bodies of water under wasting or stagnant ice. It is possible, however, that some of the deposits may have been laid down in ephemeral ice-impounded proglacial lakes.

Glaciolacustrine deposits of silt and clay, usually laminated, stone-free and with intercalated very fine-grained sand lenses and partings, crop out in the valleys of the rivers Blyth and Pont (Lawrence and Jackson, 1986). Similar sediments are also recorded in boreholes and trial pits in the Ponteland area. Other, apparently less extensive, occurrences of laminated silt and clay have been observed in cliff sections on the River Font [NZ 165 860], at Scotch Gill [NZ 1823 8610], west of Broad Law [NZ 155 799] and in site investigation boreholes west of Morpeth.

The widespread deposits of the Blyth and Pont valleys crop out below the 53 m contour between Kirkley Mill [NZ 165 767] and Bellasis Farm [NZ 194 781]. Up to 1.8 m of finely laminated silt and clay and sand laminae overlies till in natural exposures along the river courses. Laminated silt and clay, proved during site investigation work in the Ponteland area, appears to be closely associated with sand and gravel in the glacial sequence; thicknesses of individual beds do not normally exceed 2 m.

Laminated silt and clay may be more widespread than indicated by known occurrences. Most of these sediments were probably deposited in subglacial and subaerial lacustrine environments in glacial and late-glacial times.

Postglacial and recent deposits

River terrace deposits occur along the rivers Wansbeck, Font and Pont. A discontinuous veneer of sand and gravel overlying laminated clay, which flanks the River Blyth, probably also represents terrace deposits. Terrace surfaces lie between 3 and 10 m above present river level. In places, a number of individual terrace are identifiable but their lateral correlation has not been established. In the Wansbeck and Font valleys the terraces comprise sand up to 2 m thick overlying a layer of pebble and cobble gravel which, in turn, rests on till. Sections in the Pont terraces are rare but south of West Houses [NZ 1510 7227] in excess of 1.3 m of gravel in a fine sand matrix was seen to rest on till. A series of site investigation boreholes, drilled through terrace deposits at Ponteland [NZ 163 727], encountered between 1.4 and 2.0 m of gravel and sand overlain by up to 1.2 m of sandy clay with gravel. Isolated flat-topped features about 17 m above river level north-east of Buck Haughs [NZ 164 862] and west of Newminster Abbey [NZ 187 858] probably represents remanié terraces (Lawrence and Jackson, 1986).

Alluvium occurs as narrow, discontinuous tracts flanking rivers and small streams throughout the district. The alluvial deposits do not usually exceed 3 m in thickness and consist generally of laterally variable clay, silt and fine sand. In the Wansbeck valley between Bothal [NZ 240 865] and Sheepwash [NZ 256 857] the alluvium appears to consist of sand and gravel (Lawrence and Jackson, 1990). Lenses of peat, or peaty clay may be present and gravel is common at the base.

Lacustrine deposits infill small flats and hollows, throughout the district, notably at Prestwick Carr [NZ 190 740] and adjacent low ground near Ponteland. This lacustrine alluvium, which may reach in excess of 8 m in thickness, comprises sand with pebbly, silty and clayey partings. It is overlain by peat in the east. Prestwick Carr, the lake in which this alluvium was deposited, was drained as recently as 1856. Similar areas of alluvium north of Kirkharle [NZ 011 830] and adjacent to the River Blyth, south of Sandybraes, Capheaton [NZ 030 786], may, at least in part, be of lacustrine origin.

Alluvial fan deposits occur locally, where tributaries meet main streams. They occur as small deltas of alluvial material, generally similar in composition to much of the nearby river alluvium.

Marine or estuarine alluvium occur in small areas in the Wansbeck Valley north or Stakeford [NZ 273 858] and in the Blyth valley near Bedlington [NZ 276 819]. These deposits consist of silts sands and gravels.

Peat occurs in places filling small hollows or the sites of former lakes. The most extensive outcrop of peat within the district is that at Prestwick Carr [NZ 190 740] where it reaches a maximum proved thickness of 2.7 m (Lawrence and Jackson, 1986). Other significant peat accumulations include those adjacent to the River Blyth south of Cocklaw Walls [NZ 008 781], and south of Sandybraes [NZ 030 786] where up to 1.5 m of peat has been proved by augering. Similarly, peat occurs adjacent to the Matfen Burn, south of Ryal [NZ 012 731], and in Marlpit Plantation [NZ 054 723] and Fenwick Shield Plantation [NZ 056 719], both south of Fenwick, although the thickness of peat is not known at any of these localities. Peat has also been proved as beds and lenses within alluvial deposits encountered in several boreholes.

Small mounds of tufa, up to 2 m high, are currently being deposited from lime-rich water adjacent to springs at Kirkharle [NZ 0114 8273] and on the north bank of the River Wansbeck [NZ 0111 8400], north-west of Little Harle. Blocks of hard tufa up to 1 m across occur at the former locality.

Made ground

Within the western half of the district, areas of made ground are generally small and typically comprise waste rock and earth from quarry workings. Rather more extensive areas of made ground occur in and around Mootlaw Quarry [NZ 020 755] where quarry waste is used to restore worked out areas of the quarry as part of a continuous programme of landscaping and reinstatement. Within the eastern half of the district, worked out opencast coal sites are numerous. These have generally been backfilled and reinstated using waste rock previously excavated as overburden from the workings. In some places spoil from deep coalmine spoil heaps has been employed as backfill; other areas of deep mine spoil have been landscaped. Several old quarries have been filled with industrial and domestic waste.

Chapter 7 Applied geology

The Morpeth district includes part of the Northumberland and Durham Coalfield. Centuries of coal mining have had a profound influence on the social and economic history of the district and have left an indelible mark on the landscape. Deep mining of coal has now ended and, although there has been considerable production from opencast mines, there is, at the time of writing, no coal production from the district. Other mineral products include limestone, iron ore, building stone, sand and gravel, roadstone, and brick and refractory clay. Small trials have been made for lead ore. Limestone is today the only mineral product from the district.

Geological factors associated with former mining activities, present and future resources and ground stability, which should be considered in land-use planning are discussed briefly here. Sources of further information are outlined in the information sources chapter.

The key issues are:

• energy sources
• industrial and bulk minerals
• ore minerals
• water resources
• engineering geology
• abandoned coal mines
• made ground and landfill
• gases
• nature conservation

Energy sources

Coal

Although thin coal seams are known within the Dinantian rocks of the district, these have been of minor economic significance. Only the Townhead Coal, present immediately beneath the Great Limestone in the south of the district, has been worked to any extent and the amounts extracted are very small, especially when compared to the vast tonnages mined from the Westphalian Coal Measures.

A few of the rather more numerous and thicker coals within the Namurian rocks have been worked on a modest scale in several parts of the district. Most important of these has been the Little Limestone Coal; old workings may be seen at many places along its outcrop. The extent of these workings is generally unknown, though most are likely to be very small. Rather more extensive workings occur in the Stagshaw Bank area, near Little Whittington [NY 985 689], and around Kirkheaton [NZ 040 780]. The most recent attempt to work this coal within the district was at Belsay Colliery [NZ 0405 7689], near Kirkheaton, sunk in the 1930s. Despite considerable investment, including the construction of a railway to serve the mine, the venture was unsuccessful and was soon abandoned. Other Namurian coals, worked on a small scale locally, include the Oakwood Coal at Shaftoe [NZ 042 825] and near Halton [NZ 010 690], the Chapel House Coal at Stamfordham [NZ 0840 7205], and the Newton Coal at Bolam [NZ 097 820].

By far the greatest coal production from the district was obtained from the Westphalian Coal Measures of the Northumberland Coalfield. At least 20 named seams are known to have been worked, many of them extensively. Several seams are over 1 m thick. Certain seams have long been known to exhibit particular characteristics, for example the High Main Coal, which was so well suited to household use that its name was on occasions applied to other coals to boost sales. The characteristics of individual seams have been the subject of detailed study (National Coal Board, 1965). A summary of important aspects of the coals of parts of the district, together with comments on the extent of extraction of individual seams, has been given by Lawrence and Jackson (1990). Throughout the coalfield coal rank typically increases southwards in response to the higher geothermal gradients associated with the basement strata of the Alston Block, including the Weardale Granite. Within the Morpeth district there is an overall increase in coal rank from relatively low in the north to medium rank in the south. Coals from this part of the Northumberland Coalfield were formerly important as household coals and for gas making. More recently they have supplied the power station market, both locally and further afield and have, in addition, been blended with other coals for metallurgical and other uses.

Coal mining in this part of Northumberland can claim a long history, extending back over many centuries. Old bell pits and shallow surface, or near surface, workings mark the outcrop of several seams. The heyday of coal production came in the 18^th and 19^th centuries when the Northumberland and Durham Coalfield was one of the world’s major coal-producers. The district’s coal found a ready market both in the nearby industrial centres of northeast England as well as contributing to an important export trade. All underground coal mining within the district has now ended and, although resources of coal remain at depth, any resumption of underground working is considered extremely unlikely in the foreseeable future. Opencast extraction has been important within the past half century and, although none is taking place within the district at the time of writing, exploration for workable reserves has been undertaken recently.

Coalbed methane

Glover et al. (1993) concluded that coalbed methane potential of the Northumberland and Durham Coalfield is likely to be low due to low adsorbed methane, extent of mining and lack of thick cover.

Industrial and bulk minerals

A variety of deposits within the district have been exploited, though today only limestone is regularly worked.

Most of the Dinantian and Namurian limestones have been worked to some extent. Many of these workings were on a very modest scale producing small amounts of lime mainly for nearby agricultural use. Small quarries, commonly with associated limekilns, may be seen throughout the district. Limestone quarrying today is restricted to one large quarry at Mootlaw, near Matfen [NZ 020 757]. Here the Great Limestone is worked as a source of crushed rock aggregate and as a subbase for road construction. Much of the exposed outcrop of limestone has today been extracted and the worked ground landscaped. Further reserves are now being extracted beneath an increasing thickness of overburden comprising mainly Namurian mudstones and sandstones.

Dolerite of the Whin Sill crops out in several places around Kirkwhelpington in the extreme north-west of the district. The quartz dolerite of this intrusion provides a good roadstone, used widely in northern England, and is worked on a large scale in the adjoining districts. It was formerly worked at East White Hill Quarry, north of Kirkwhelpington [NY 9948 8576]. Apart from a tiny and long abandoned pit at Bolam [NZ 0945 8217] the dolerite dykes associated with the Whin Sill have not been worked. Small quarries were formerly worked in Tertiary dolerite dykes south of Bedlington [NZ 264 815] and on the south bank of the River Wansbeck [NZ 2127 8612] east of Morpeth. A resumption of dolerite quarrying within the district is unlikely.

A few sandstone quarries were formerly worked on a larger scale, some to provide stone for use outwith the district. These include the quarries around Ingoe [NZ 038 748] in the sandstone above the Little Limestone, at Harlow Hill [NZ 0775 6874] in the sandstone above the Newton Limestone, at Dalton [NZ 1140 7190] in the sandstone above the Dalton Limestone, and at Rivergreen [NZ 1235 8405] in the upper part of the Stainmore Group. Part of the sandstone that occupies much of the succession between the Corbridge and Thornbrough limestones was worked in a series of quarries at Belsay to provide stone for Belsay Hall and for cottages on the estate. Although capable of providing large blocks of a generally pale brown colour and even medium-grain size the stone locally contains numerous small clusters of pyrite crystals. Oxidation of this produces distinctive ochreous spots which, although disfiguring the stone, do not appear to weaken it. A Coal Measures sandstone formerly quarried at Hartford [NZ 241 800] is said to have provided stone for repairs to the Houses of Parliament and two London bridges. Another Coal Measures Sandstone, above the Kirkby’s Marine Band and known locally as the Woodhorn Sandstone, was widely used in the past both as a building stone and for the making of grindstones, many of which were exported to Norway and Sweden (Lawrence and Jackson, 1990a). Considerable amounts of sandstone, some perhaps of sufficient quality to be used for building stone, remain within the district.

Mudstone and siltstone from the Coal Measures have been worked for brick materials, often as a by-product of coal mining, at several places in the Northumberland Coalfield. The seatearths of some coal seams, for example the High Main, Five-Quarters and Low Main, consist of high-alumina clays (sometimes referred to as seggar) suitable for the manufacture of refractory products. The latter seatearth was mined locally in the Netherton area [NZ 230 827]. Further reserves of these materials may be workable in conjunction with opencast coal extraction.

Superficial deposits have been worked locally for brick and tile making. Clay has been exploited where it is relatively stone-free (and possibly laminated); it occurs as lenses within the complex glacial deposits, that fill the buried valley of the Sleek Burn between Scotland Gate [NZ 250 840], and Red Row [NZ 273 838]. (Lawrence and Jackson, 1990). Bricks and tiles were made from till at Capheaton [NZ 0355 8085] and from alluvium at Belsay [NZ 1130 7825]. A fine row of abandoned kilns remains at the latter site.

Sand and gravel has been worked, mainly on a small scale, from several small pits in the larger areas of superficial deposits.

Ore minerals

Ironstone in the form of siderite mudstone (‘clay ironstone’) nodules is locally common within some Carboniferous mudstones. They are particularly abundant in parts of the Coal Measures where they occur as scattered nodules, or layers of nodules, above some coal seams. As in other British coalfields, it is likely that these ironstones were worked on a small scale from a very early date. Within this district, clay ironstone nodules that occur in beds above the Northumberland Low Main Coal were worked in the Netherton area [NZ 233 823]. Ore from here fed the Bedlington Iron and Engine Works [NZ 278 821], which stood on the banks of the River Blyth, near Furnace Bridge. This works played an important role, both nationally and internationally, in the development of early railways and was closely associated with such pioneering names as Stephenson and Longridge. Such ores typically contain up to about 25 per cent metallic iron and, although formerly workable, they are too low grade to attract economic interest today.

Trials for lead ore are known at two localities within the district. In the early 19th century, shafts and adits were driven in search of lead ore on an east-west fault vein which cuts the Whin Sill and Liddesdale Group strata from the Upper Bath-House Wood and Shotto Wood limestones on the south bank of the River Wansbeck at Kirkwhelpington (Smith, 1923). The venture was unsuccessful and little if any ore was raised. A few blocks of limestone veined by calcite and grey shale remain on the small, overgrown spoil heap from a shaft [NY 9956 8424]. Small trial workings for lead ore may also be seen at Sandybraes, near Capheaton [NZ 0317 7904]. The small spoil heaps from what appear to be shallow shafts and adits contain a little galena and baryte together with dolerite. No records have been found for this trial. The mineralisation seems to occur in association with the Whin dyke here intruded into the eastward continuation of the Hallington Reservoir Fault of the Bellingham district to the west.

Water resources

The Morpeth district is situated largely within the catchment of the River Blyth, which flows from the southwestern corner of the district to reach the sea at Blyth. The northernmost quarter of the district drains to the Wansbeck catchment: rivers that rise west of the district flow eastwards through Morpeth and reach the sea at North Seaton. Two small portions of the district, the southernmost edge on the outskirts of Newcastle, and the eastern margin above the Hallington Reservoirs, drain to the Tyne.

The land surface on the interfluves rises steadily away from the coast and reaches 177 m above OD at Slate Hill [NZ 082 765] and 258 m above OD at Moatlaw [NZ 010 759]. The River Blyth is gauged at Hartford Bridge [NZ 243 800] below a catchment area of 269 km2. The Baseflow Index at this point is 0.34, suggesting that a third of the long-term discharge derives from groundwater arriving in the river as baseflow. This is a relatively low proportion of river flow for a lowland catchment, but may reflect the almost continuous cover of till which inhibits recharge and, therefore, also the volume of groundwater flowing through the aquifer. Mean annual precipitation for the catchment is 700 mm, but effective rainfall (mean annual precipitation minus evapotranspiration) is only about 250 mm.

All the bedrock strata within the district are, to a greater or lesser degree, water bearing, although none comprises a regionally important or major aquifer. In general, groundwater flows from beneath the higher land to the west in an easterly direction towards the sea. The average hydraulic gradient is about 1:150 and a likely range of hydraulic conductivity for the upper 50 m of relatively weathered and fractured ground may lie in the range 0.1 to 10 md^-1 ; the higher values are typical of arenaceous material and the lower values more representative of the shaly strata. The shallow coal workings and associated disturbed ground of the Coal Measures and parts of the Stainmore Group are likely to exhibit enhanced permeability with a potential for relatively rapid groundwater transport.

There has been a traditional reliance on groundwater, particularly in the valleys where springs and shallow wells have exploited the relatively shallow water table. These sources have now largely been abandoned in favour of mains water, and in places by deeper borehole supplies, most of which are still dedicated for private use.

Recorded borehole yields in the district are, with two exceptions, less than 3 ls^-1. The exceptions are both at Morpeth, one of which, the deep Abbey Well Borehole [NZ 2015 8580], is described below. The other is an exploratory borehole [NZ 2223 8479], 200 m deep, where a yield of 6.3 ls^-1 was tested for a 48 hour period to create a drawdown of 69 m; the borehole penetrated Lower and Middle Coal Measures. A borehole drilled between Pegswood and Morpeth [NZ 212 869] just in the Rothbury district to the north was tested at 40 ls^-1  for a drawdown of 4 m, but this almost certainly reflects intersection of the borehole with a former coal working or goaf (area of coal extraction) horizon. Otherwise, sustainable borehole yields are small (Table 7), although sufficient to supply domestic and farm requirements as well as other light industry. The majority of water boreholes in the Stainmore Group are situated on the eastern half of the outcrop area. The mean drilled depth of the 98 water boreholes recorded in the district is 72 m, ranging from 10 m to 200 m.

Although groundwater in the Coal Measures was not a significant problem when the relatively shallow coal workings of the district were being mined, shaft pumping was nevertheless required. There were also several boreholes sunk specifically to assist in dewatering, although this was more common down dip to the east of the district, for example at Woodhorn near North Seaton [NZ 2925 8737].

The most celebrated groundwater source is the group of boreholes that includes the so-called Abbey Well source, which supplies a bottled water and soft drinks plant at Morpeth. The main source is a borehole 118 m deep which penetrates glacial and Recent sands over till to a depth of 33 m, then passes through sandstones and shales in the

Coal Measures, including the Marshall Green or Victoria Coal, and into the sandstones of the Morpeth Group with sandy shale and mixed shale and coal between 112 and 117 m depth. The borehole provides an exceptional sustainable yield of 6 ls^-1, but other boreholes at the same site are lower yielding. Representative major ion chemistry for the Abbey Well source is given in (Table 8). It has a distinctively high Mg to Ca ratio, as well as a high K ion concentration, which may reflect mature water that has undergone extensive water-rock interaction over a long period.

Groundwater chemistry in parts of the Coal Measures, along with issues into former mine workings, are typically highly alkaline. Postdepositional flushing of the arenaceous beds with sea water and subsequent base exchange generated highly saline waters, such as those described for the Backworth Eccles Pit in the Tynemouth district to the east by Edmunds (1975). Samples from different levels in this pit showed that the barium concentration ranged from 8000 to 36 000 times that of sea water, a factor that was exploited until 1978 for the production of industrial grade barium sulphate for the paint industry (Banks et al., 1996). Elsewhere in the Coal Measures and Stainmore Group groundwater is generally moderately mineralised with less than 750 mg l^-1 total dissolved solids (Table 8). These groundwaters are typically of the calcium-bicarbonate type of near neutral acidity.

With the ending of deep coal mining within the district pumping from collieries has ceased. Dewatering at Blyth was discontinued in the late 1980s, and pumping from the shaft of the former Dinnington Colliery [NZ 232 728] and Seaton Delaval Colliery [NZ 300 750] just east of the district had then also ceased, although these shafts are retained to observe groundwater levels, which were respectively 56 and 81 m below OD in 1988 (Harrison et al., 1989). Water in abandoned coal workings reacts, in the presence of air, with pyrite within the coal and associated rocks, to produce highly ferruginous waters, commonly with a very low pH. Regional recovery of the water table may result in discharges to surface of such acid mine water, which may cause serious pollution (see below).

Engineering geology

The range of geological materials within the district exerts an important influence on ground conditions and thus on civil engineering construction and land use. These materials can be divided into three groups: superficial deposits, bedrock and made ground. Local geological and topographical conditions may influence the development of landslipping and flooding.

Included below is a brief summary of important aspects of the district’s geology relevant to ground engineering. Further details on the engineering properties and geological hazards in the Morpeth district can be found in Donnelly (1998) and Lawrence and Jackson (1986; 1990).

The noncohesive superficial deposits, such as alluvial sands, glacial sands and gravels, are granular, composed mainly of sand and gravel, with silt and clay layers. In general, these deposits provide adequate bearing capacity for most domestic or light industrial purposes. Where of low density (loose) they will have a lower bearing capacity. These deposits can be excavated relatively easily, they are diggable but trench supports may be necessary and dewatering may be required in excavations below the water table. When foundations are to be sunk in these deposits, site investigation is required to determine their highly variable nature. Cuttings will require drainage measures to remove water from perched water tables and relieve relatively high water pressures in confined aquifers, such as sands and gravels overlain by less permeable clays, to avoid sagging or heave on excavation. Till is the most widespread superficial deposit in the district. A surface weathered layer occurs that is less dense, weaker, more plastic and has a higher moisture content than the underlying material, and can exist up to a depth of at least 8 m. Reverse strength gradients and perched water tables may occur in sand and gravel layers. Boulders and rafted bodies of bedrock in till should be considered when drilling, since these are frequently mistaken for the bedrock surface. Alluvial clays and laminated silts and clays are cohesive, very soft to soft, highly compressible and are of a low bearing capacity. Lightweight structures will require special foundations to spread the load or piles to transfer the load to a deeper, stronger stratum. The deposits vary laterally in composition and structure, leading to differential settlement where structures cross composition boundaries. Gravel layers within these deposits provide better foundation conditions. However, these require site investigation procedures to determine the variations within, and extent of, the gravel layers. Peat is an organic soil. It is highly compressible and may stand well without support in excavations if fibrous. However, amorphous peat will flow and therefore requires close boarding.

The bedrock in the district is strong with an adequate bearing capacity for domestic and light industrial structures using normal foundations. However, rock mass discontinuities such as joints and faults, and weathering or the presence of groundwater will significantly reduce the strength of rock. Solution hollows may present a significant hazard in the limestones. These can result in subsidence and may contain abnormally high concentrations of radon gas. On the Coal Measures outcrop instability should be anticipated associated with mining, such as subsidence, fault reactivation and the collapse of mine workings. Detailed site investigations are required.

Made ground (artificial deposits) include backfilled quarries, landfill sites, abandoned opencast coalmines, waste sites, landscaped and disturbed ground. These display a wide range of geotechnical properties. Leachate plumes, solid and liquid contaminants, potentially explosive and noxious gasses and uneven ground settlement have implications for health and foundation construction. These sites should always be thoroughly investigated.

Landslides may occur where the slopes have been oversteepened, both naturally and artificially.

Flooding may follow the cessation of pumping in the deep mines; the regional recovery of the watertable may result in acid mine-water discharge.

Abandoned mining areas

It is essential, prior to any development in mining regions, that the extent and depth of any abandoned mining areas is determined accurately. However, this can be difficult to ascertain for the oldest workings. The earliest workings are likely to have been at outcrop. By the end of the 13th century, coal was being extracted from shallow drifts or adits and bell-pits. In Medieval times deeper reserves were worked from shafts by the technique of underground mining known as room and pillar (pillar and stall or board and pillar). In this method, pillars of coal were left unworked to support the roof. Extraction rates varied between 40 and 80 per cent. More recently, mechanised longwall mining has led to almost total extraction in large areas of some seams.

In the 20th century, mechanised earth movers made large-scale open cast coal mining practical. Whereas the initial sites developed in the 1940’s were seldom more than 20 m deep, in recent years much more extensive pits have been worked, in some instances to depths of about 100 m.

Particular hazards presented by abandoned mine workings include:

• collapse or movement of the ground, including reactivation of pre-existing faults
• discharge of acid minewaters from flooded workings
• gases
• abandoned mine shafts and adits

The collapse or movement of the ground, including reactivation of pre-existing faults, may occur suddenly, or gradually and may be induced by such factors as changes in water levels, additional surface loading, vibration from traffic, further mining subsidence, or blasting. Near-surface room and-pillar workings may not collapse completely when mining has ceased (Plate 6). However, with time failure is possible by the collapse of the roof beds spanning adjacent pillars, pillar failure can occur and the floor and roof strata can bulge and squeeze into the void (Piggot and Eynon, 1978). Subsidence over areas of former longwall mining is usually completed after around 12 months, although residual subsidence may continue for several years. The role of rising water levels in old workings in mining-induced fault reactivation has been described by Donnelly (1994).

The discharge of acid minewaters from flooded workings is a likely consequence of the regional recovery of the water table after the ending of mine pumping; this can result in the discharge to surface of large volumes of acid water. Water may reach the surface in a variety of ways, for example through abandoned mine openings or boreholes, or through fissured ground. Such minewaters can result in contamination to water supplies and rivers, the precipitation of heavy metal and/or iron oxide ochreous deposits and flooding of buildings. Recent reviews of the environmental consequences of minewater recovery include Harrison et al. (1989), National Rivers Authority (1994; 1996), Robins and Younger (1996) and Younger (1994; 1995a, b; 1997, 1998)

In common with most British coalfields, the Coal Measures of Northumberland are known to yield significant quantities of methane or ‘fire damp’. Concentrations of between 5 to 15 per cent with air are potentially explosive. Methane continues to be released into abandoned coal workings where significant volumes may accumulate. Hydrogen sulphide, carbon dioxide and other gases may be generated in old workings. Oxidation processes taking place in old workings may result in the accumulation of oxygen-deficient air, commonly known as ‘stythe’ or ‘blackdamp’. This is an asphyxiating mixture, mainly of carbon dioxide and nitrogen. All of these gases may be trapped in old workings or porous rocks beneath an impermeable cover such as till. Discharge into the atmosphere can occur through natural fissures, shafts or adits, through collapsed old workings or through porous rocks such as sandstones. Such gas emissions may be more pronounced during periods of low atmospheric pressure. Rising water levels in old workings may displace gas accumulations. Where there is no continuous, impermeable cover the discharge of gases may take place over a wide area giving rapid dilution by the air. In these circumstances the gas emissions may pose little risk to health. In other situations where an impermeable seal, which normally confines volumes of gas, is breached potentially dangerous emissions may occur. The construction of boreholes, sewers and water pipes and other deep excavations can form pathways through which gases may readily pass and in which they may collect. Advice on the treatment of old workings with regard to gas emissions and other related hazards is available (National Coal Board, 1982). In a recent national assessment Appleton (1995a, b) and Appleton et al. (1995) considered the Coal Measures outcrop of the district to be an area of moderate susceptibility to methane and carbon dioxide emissions; the remainder of the district was considered an area of generally low susceptibility though with some areas of moderate susceptibility.

Little information is available on radon concentrations in the district. However, in a recent national assessment, Appleton and Ball (1995) considered the outcrops of the Liddesdale and Stainmore Group rocks as areas of moderate radon potential; the Coal Measures outcrop was classified as an area of low to moderate radon potential though with local areas susceptible to moderate or high levels of radon emissions.

Whereas a very large number of shafts and adits are recorded in the district it is likely that there are many more for which no records exist. Many old shafts may be inadequately filled or capped and may present significant hazards. A fall down a mineshaft results in almost inevitable serious injury or death. Moreover, such abandoned mine entrances may act as pathways for gas or water emissions. The collapse of these openings is also possible. Whenever the presence of old shafts or adits is suspected it is essential that they are located and adequately treated. A range of geophysical and other site investigation techniques are available to undertake this task. Advice on the treatment of disused shafts and adits is available (National Coal Board, 1982).

Nature conservation

There are currently no sites designated as geological Sites of Special Scientific Interest (SSSI) within the district. However, a few sites of local conservation interest, for their geological and other natural history importance, are designated as Sites of Nature Conservation Importance (SNCI). At the time of writing a number of these, and other sites with significant educational value, are under consideration for designation as Regionally Important Geological and Geomorphological Sites (RIGS). Details of these may be obtained from The Royal Society for Nature Conservation, The Kiln, Mather Road, Newark NG24 1WT.

Information sources

Further geological information held by the British Geological Survey relevant to the Morpeth district is listed below. It includes published maps, memoirs and reports and open-file maps and reports. Other sources include borehole records, mine plans, fossils, rock samples, thin sections, hydrogeological data and photographs.

Searches of indexes to some of the collections can be made on the Geoscience Index system in British Geological Survey libraries. This is a developing computer-based system which carries out searches of indexes to collections and digital databases for specified geographical areas. It is based on a geographic information system linked to a relational database management system. Results of the searches are displayed on maps on the screen. At the time of writing (1998) the data sets are limited and not all are complete. The available indexes are as follows:

• index of boreholes
• topographical backdrop based on 1:250 000 scale maps
• outlines of British Geological Survey maps at 1:50 000,
• 1:10 000, 1:10 560 scales and County Series maps
• chronostratigraphical boundaries and areas from British Geological Survey 1:250 000 scale maps
• geochemical locations
• aeromagnetic and gravity data recording stations
• land survey records

Details of geological information available from the British Geological Survey can be accessed on the BGS Web Home Page at http://www.bgs.ac.uk

BGS maps

Geological maps

1:625 000

• United Kingdom North Sheet, Solid geology, 1979, Quaternary geology, 1977

1:250 000

• 55N 04W Borders, Solid geology, 1986 55N 02W Farne, Solid geology, 1988

1:63 360

• Sheet 9 Rothbury, Solid, 1934
• Sheet 15 Tynemouth, Solid and drift, 1934

1:50 000

• Sheet 8 Elsdon, Solid with drift, 1951 (reprinted 1993), Solid and drift, 1951 (reprinted 1993)
• Sheet 9 Rothbury, Solid and drift, 1977
• Sheet 10 Newbiggin, Solid 1997, Solid with drift, 1997
• Sheet 13 Bellingham, Solid with drift, 1980, Solid and drift, 1980
• Sheet 14 Morpeth, Solid and drift, 1977
• Sheet 15 Tynemouth, Solid with drift, 1975
• Sheet 19 Hexham, Solid, 1975
• Sheet 20 Newcastle upon Tyne, Solid and drift, 1992
• Sheet 21 Sunderland, Solid 1978, Drift, 1978

1:10 000 and 1:10 560

The original geological survey was undertaken at a scale of six inches to one mile (1:10 560) by H H Howell, W Topley, G A L Lebour and G Barrow with the first results published, as Sheet 105NW [Old Series] in 1892. A revision survey at 1:10 560 scale, conducted between 1922 and 1937 by W Anderson, G A Burnett, V A Eyles and A Fowler, was published as Sheet 14 Morpeth in 1955. Small areas along the western, southern and eastern margins of the district were resurveyed between 1959 and 1983, as part of the revision survey of sheets 13 Bellingham, 20 Newcastle and 15 Tynemouth, respectively, by D W Holliday, D H Land, D A C Mills, G Richardson, J G O Smart, and D B Smith. Systematic revision of the coalfield areas at 1:10 000 scale was carried out between 1983 and 1989 by I Jackson, D V Frost and D J D Lawrence. Resurvey of the Liddesdale and Morpeth Group outcrops at 1:10 000 scale was carried out by B Young and D J D Lawrence between 1994 and 1996.

Geological 1:10 000 and 1:10 560 scale National Grid maps included in whole or in part in the 1:50 000 scale Sheet 14 Morpeth are listed below, together with the initials of the geological surveyors and dates of survey.

Copies of the fair-drawn maps have been deposited in the British Geological Survey libraries in Edinburgh and at Keyworth for public reference and may also be inspected in the London Information Office, in the Natural History Museum, South Kensington, London. Copies may be purchased directly from the British Geological Survey as black and white dyeline copies.

Applied geological maps

1:625 000

The geographical extent and geological relationships of contamination from natural sources and mining areas is presented on national summary maps to accompany BGS Technical Reports, WP/95/1 to 4. These were prepared to aid the consideration of whether the areas affected by ‘natural’ and mine-related contamination may require consideration by planners, developers and other potential users, especially where new development or remedial work on land is planned.

• Methane, carbon dioxide and oil seeps from natural sources
• Radon and background radioactivity from natural sources
• Potentially harmful elements from natural sources and mining areas
• Radon, methane, carbon dioxide, oil seeps and potentially harmful elements from natural sources and mining areas

1:25 000

A set of thematic maps prepared for land-use planning is available for the Morpeth-Bedlington-Ashington area. These normally accompany BGS Technical Report, WA/90/14, 1990, but they can be obtained separately. Maps to accompany this report for NZ28/38 are as follows:

• solid geology
• drift geology
• rockhead elevation
• drift thickness
• made and disturbed ground
• shallow mining
• borehole and shaft sites
• engineering geology
• mineral and water resources and extraction (excluding coal)
• geological factors for consideration in land-use planning

Maps showing structure contours and shallow coal workings accompany the BGS Research Report, 1986, Geology of the Ponteland-Morpeth district.

1:10 000

A set of thematic maps prepared for land-use planning is available for the Ponteland-Morpeth area. These normally accompany the BGS Research Report 1986, Geology of the Ponteland- Morpeth district, but can be obtained separately. For each of the component 1:10 000 scale maps, NZ17NE, NZ17SE, NZ18NE and NZ18SE the following thematic maps are available:

• Solid and drift geology
• Rockhead elevation
• Drift thickness
• Borehole and shaft sites^‡1 

Geophysical maps

1:1 500 000

• Colour shaded relief gravity anomaly map of Britain, Ireland and adjacent area, 1997
• Colour shaded relief magnetic anomaly map of Britain, Ireland and adjacent area, 1998

1:625 000

• Aeromagnetic map of Great Britain (and Northern Ireland), South sheet, 1965
• Bouguer anomaly map of the British Isles, Southern sheet, 1986

1:250 000

• 55N 04W Borders, Aeromagnetic anomaly, 1981; Bouguer anomaly, 1981
• 55N 02W Farne, Aeromagnetic anomaly, 1978; Bouguer anomaly, 1978

1:50 000

Geophysical Information Maps; plot-on-demand maps are available which summarise graphically the publicly available geophysical information held for the sheets in the BGS databases. Features include:

• regional gravity data: Bouguer anomaly contours and location of observations
• regional aeromagnetic data: total field anomaly contours and location of digitised data points along flight lines
• gravity and magnetic fields plotted on the same base map at 1:50 000 scale to show correlation between anomalies
• separate colour contour plots of gravity and magnetic fields at 1:125 000 scale for easy visualisation of important anomalies
• location of local geophysical surveys
• location of public domain seismic reflection and refraction surveys
• location of deep boreholes and those with geophysical logs

Geochemical atlases

• The Geochemical Baseline Survey of the Environment (G-BASE) is based on the collection of stream sediment and stream water samples at an average density of one sample per 1.5 km2. The fine (minus 150 m) fractions of stream sediment samples are analysed for a wide range of elements, using automated instrumental methods.
• The samples for southern Scotland and northern England were collected between 1977 and 1986. The results (including Ag, As, Ba, Be, Bi, B, CaO, Cd, Co, Cr, Cu, Fe₂O3, Ga, K₂O, La, Li, MgO, Mn, Mo, Ni, Pb, Rb, Sb, Sn, Sr, TiO2, U, V, Y, Zn, and Zr in stream sediments, and pH, conductivity, fluoride, bicarbonate and U for stream waters) are published in atlas form (Regional geochemistry of Southern Scotland and part of Northern England, 1993). The geochemical data, with location and site information, are available as hard copy for sale or in digital form under licensing agreement. The coloured geochemical atlas is also available in digital form (on CD-ROM or floppy disc) under licensing agreement. BGS offers a client-based service of interactive GIS interrogation of the G-BASE data.

Hydrogeological map

1:625 000

• England and Wales, 1977

BGS books

The various books, memoirs and reports relevant to the Morpeth district are listed in the reference section. Bulletins and reports, including BGS Technical Reports, are not widely available but may be purchased from the BGS or consulted at the BGS and other libraries.

The district lies within the Northern England area of the British Regional Geology series of publications (Taylor et al., 1971), which are readily available in British Geological Survey and some other bookshops. Other aspects of the general geology can be found in British Geological Survey Memoirs (Fowler, 1936; Day, 1970; Land, 1974; Frost and Holliday, 1980), and Technical and special reports (Jackson et al., 1985; Lawrence and Jackson, 1986; Chadwick et al., 1995; Jones, 1996; Young 1998; Young and Lawrence, 1998). Petrological details appear in Bulletins of the Geological Survey of Great Britain (Harrison, 1968), Reports of the Institute of Geological Sciences (Dunham and StrasserKing, 1982) and Technical Reports (Beddoe-Stephens, 1998). There is biostratigraphical data in Technical Reports (Owens, 1972; Brand, 1987; 1990; 1991; Dean, 1996; Dean and Brand, 1998; Riley, 1998a; 1998b). Mineral resource information occurs in BGS Economic Geology Memoirs (Dunham, 1990) and special reports (Smith, 1923). Information on non-mineral resources is present in Technical Reports (Glover et al., 1993; Harris, 1993), as is the case for that on Land-use planning (Lawrence and Jackson, 1990a, b; Appleton, 1995a, b; Appleton and Ball, 1995; Appleton et al., 1995). There is information on engineering geology in technical reports (Donnelly, 1998).

Documentary collections

BGS holds collections of borehole and site investigation records, which may be consulted at BGS, Edinburgh. Index information for these boreholes has been digitised. The logs are either hand-written or typed and many of the older records are driller’s logs.

Materials collections

Geological survey photographs illustrating aspects of the geology of the district are deposited for reference in the libraries at BGS, Edinburgh, and BGS, Keyworth. Sheet albums of the more recent photographs are also held in the BGS Information Office, London. The older photographs are in black and white; later photographs are in colour. They depict rocks and sediments in natural or manmade exposures, general views illustrating the influence of geology and examples of mining activity and its effect on the landscape. Copies of the photographs may be purchased as black and white or colour prints, and 50 × 50 mm transparencies.

The petrological collections of BGS include a small number of rock specimens and associated thin sections from the district. Included are samples of limestone, mudstone, bitumen-bearing calcite and dolerite.

BGS holds collection of rock and biostratigraphical specimens from approximately 300 boreholes in the Morpeth district. In addition there are more than 1800 registered biostratigraphical specimens collected from surface outcrops, temporary exposures and boreholes throughout the district. For further information on, and access to, the macrofossil collection contact should be made with The Curator, Scotland and Northern England Group Palaeontology Unit, BGS Edinburgh.

Relevant collections held outside BGS

Coal abandonment plans are held by The Coal Authority, Mining Records Department, Bretby Business Park, Ashby Road, Burtonon-Trent, Staffs, DE15 0QD.

References

Most of the references listed below are held in the libraries of the British Geological Survey at Murchison House, Edinburgh and at Keyworth, Nottingham. Copies of the references can be purchased from the Keyworth office subject to the current copyright legislation.

ARMSTRONG, H A, and PURNELL, M A. 1987. Dinantian conodont biostratigraphy of the Northumberland Trough. Journal of Micropalaeontology, Vol. 6, 97-112.

APPLETON, J D. 1995a. Radon, methane, carbon dioxide, oil seeps and potentially harmful elements from natural sources and mining areas relevant to planning and development in Great Britain. British Geological Survey Technical Report, WP/95/4.

APPLETON, J D. 1995b. Potentially harmful effects from natural sources and mining areas; characteristics, extent and relevance to planning and development in Great Britain. British Geological Survey Technical Report, WP/95/3.

APPLETON, J D, and BALL, T K. 1995. Radon and background radioactivity from natural sources: characteristics, extent and relevance to planning and development in Great Britain. British Geological Survey Technical Report, WP/95/2.

APPLETON, J D, HOOKER, P J, and SMITH, N J P. 1995. Methane, carbon dioxide and oil seeps from natural sources and mining areas: extent and relevance to planning and development in Great Britain. British Geological Survey Technical Report, WP/95/1.

BANKS, D, YOUNGER, P L, and DUMPLETON, S. 1996. The historical use of mine-drainage and pyrite oxidation waters in central and eastern England, UK. Hydrogeology Journal, Vol. 4, 55-68.

BATESON, J H, JOHNSON, C C, and EVANS, A D. 1985. Follow-up mineral reconnaissance investigations in the Northumberland Trough. Mineral Reconnaissance Report, Institute of Geological Sciences, No. 77.

BEAUMONT, P. 1968. A history of glacial research in northern England from 1860 to the present day. University of Durham Department of Geography Occasional Paper, Series 9.

BEDDOE-STEPHENS, B. 1998. Petrography of dolerite dykes from the Morpeth district. British Geological Survey, Mineralogy and Petrology Short Report, No. MPSR/98/6.

BOTT, M H P, and 5 others. 1985. Crustal structure south of the Iapetus suture beneath northern England. Nature, London, Vol. 314, 724-727.

BOYD, E F. 1861. On a part of the Carboniferous or Mountain Limestone series in north Northumberland. Transactions of the North of England Institute of Mining and Mechanical Engineers, Vol. 9, 122.

BRAND, P J. 1987. Report on the palaeontology of various NCB [British Coal] Opencast Executive boreholes drilled in the area of the deeper boreholes at Broad Law and Tranwell. British Geological Survey Technical Report, PD/87/315.

BRAND, P J. 1990. Report on specimens from Mootlaw Quarry provided by A Pringle Esq. British Geological Survey Technical Report, WH/90/162R

BRAND, P J. 1991. Report on a collection of fossils from Glororum Opencast Site, Sheet 14 England, NZ18SE. British Geological Survey Technical Report, WH/91/76R.

BURGESS, I C, and HOLLIDAY, D W. 1979. Geology of the country around Brough-under-Stainmore. Memoir of the Geological Survey of Great Britain, Sheet 31 and parts of 25 and 30 (England and Wales).

CALVER, M A. 1969. Westphalian of Britain. Compte Rendu 6me Congrès International de Stratigraphie et de Géologie du Carbonifère, Sheffield, 1967, Vol. 1, 233-254.

CHADWICK, R A, and HOLLIDAY, D W. 1991. Deep crustal structure and Carboniferous basin development within the Iapetus convergence zone, northern England. Journal of the Geological Society of London, Vol. 148, 41-53.

CHADWICK, R A, HOLLIDAY, D W, HOLLOWAY, S, and HULBERT, A G. 1993. The evolution and hydrocarbon potential of the Northumberland-Solway Basin. 717-726 in Petroleum geology of northwest Europe: Proceedings of the 4th Conference. PARKER, J R (editor). Vol. 1. (London: The Geological Society.)

CHADWICK, R A, HOLLIDAY, D W, HOLLOWAY, S, and HULBERT, A G. 1995. The structure and evolution of the Northumberland-Solway Basin and adjacent areas. Subsurface memoir of the British Geological Survey.

CLARK, R. 1970. A short note on small meltwater channels and “microchannels” at Shaftoe Crags, Northumberland. Proceedings of the Yorkshire Geological Society, Vol. 38, 57-59.

CREANEY, S, JONES, J M, HOLLIDAY, D W, and ROBSON, P. 1980. The occurrence of bitumen in the Great Limestone around Matfen, Northumberland — its characterisation and possible genesis. Proceedings of the Yorkshire Geological Society, Vol. 43, 69-79.

CUMING, J S. 1970. Rock-head relief of south-east Northumberland and the lower Tyne Valley. Unpublished PhD thesis, University of Newcastle upon Tyne.

CUMING, J S. 1977. A descriptive account of the buried rockhead topography of Tyneside. In FULLERTON, B (editor), North eastern studies. Department of Geography, University of Newcastle upon Tyne.

DAY, J B W. 1970. Geology of the country around Bewcastle. Memoir of the Geological Survey of Great Britain, Sheet 12 (England and Wales).

DEAN, M T. 1996. Conodont biostratigraphic control for Carboniferous limestone sporadically exposed in the area of geological Sheet 14. British Geological Survey Technical Report, WH/96/106R.

DEAN, M T, and BRAND, P J. 1998. English Sheet 14 (Morpeth). A palaeontological and biostratigraphical summary. British Geological Survey Technical Report, WM/98/77R

DONNELLY, L J. 1994. Predicting the reactivation of geological faults and rock mass discontinuities during mineral exploration, mining subsidence and geotechnical engineering. Unpublished PhD thesis, University of Nottingham.

DONNELLY, L J. 1998. The engineering geology of the Morpeth area 1:50 000 geological Sheet 14. British Geological Survey Technical Report, WN/98/2.

DUNHAM, A C. 1982. Late Carboniferous intrusions of northern Britain. 277-283 in Igneous rocks of the British Isles. SUTHERLAND, D S (editor). (New York: John Wiley.)

DUNHAM, A C, and STRASSER-KING, V E H. 1981. Petrology of the Great Whin Sill in the Throckley Borehole, Northumberland. Report of the Institute of Geological Sciences, No. 81/4.

DUNHAM, K C. 1950. Lower Carboniferous sedimentation in the Northern Pennines (England). 46-63 in Report of the 18th session of the International Geological Congress, Great Britain, 1948.

DUNHAM, K C. 1990. Geology of the Northern Pennine Orefield: Volume 1, Tyne to Stainmore. Economic Memoir of the British Geological Survey, Sheets 19 and 25 and parts of 13, 24, 26, 31, 32 (England and Wales).

DWERRYHOUSE, A R. 1902. The glaciation of Teesdale, Weardale and the Tyne Valley, and their tributary valleys. Quarterly Journal of the Geological Society of London, Vol. 58, 572-608.

EDMUNDS, W M. 1975. Geochemistry of brines in the Coal Measures of northeast England. Transactions of the Institution of Mining and Metallurgy (Section B: Applied earth science), Vol. 84, B39-B52.

ELLIOT, T. 1975. The sedimentary history of a delta lobe from a Yoredale (Carboniferous) cyclothem. Proceedings of the Yorkshire Geological Society, Vol. 40, 505-536.

EVANS, A D, and CORNWELL, J D. 1981. An airborne geophysical survey of the Whin Sill between Haltwhistle and Scots’ Gap, south Northumberland. Mineral Reconnaissance Report, Institute of Geological Sciences, No. 47.

EVANS, C J, KIMBELL, G S, and ROLLIN, K E. 1988. Hot dry rock potential in urban areas. Investigation of the geothermal potential of the UK. (Keyworth, Nottingham: British Geological Survey).

EYLES, N and SLADEN, J A. 1981. Stratigraphy and geotechnical properties of weathered lodgement till in Northumberland, England. Quarterly Journal of Engineering Geology, Vol. 14, 129-141.

FAIRBAIRN, R A. 1978. Lateral persistence of beds within the Great Limestone (Namurian, E1) of Weardale. Proceedings of the Yorkshire Geological Society, Vol. 41, 533-544.

FOWLER, A. 1936. The geology of the country around Rothbury, Amble and Ashington. Memoir of the Geological Survey of Great Britain, Sheets 9 and 10 (England and Wales).

FRANCIS, E A. 1970. Quaternary. 134-152 in Geology of Durham County. HICKLING, G (editor) Transactions of the Natural History Society of Northumberland, Vol. 41, No. 1.

FRASER, A J, and GAWTHORPE, R L. 1990. Tectonostratigraphic development and hydrocarbon habitat of the Carboniferous in northern England. 49-86 in Tectonic events responsible for Britain’s oil and gas reserves. HARDMAN, R F P, and BROOKS, J (editors). Geological Society of London Special Publication, No. 55.

FREEMAN, B, KLEMPERER, S L, and HOBBS, R W. 1988. The deep structure of northern England and the Iapetus Suture zone from BIRPS deep seismic reflection profiles. Journal of the Geological Society of London, Vol. 145, 727-740.

FROST, D V, and HOLLIDAY, D W. 1980. Geology of the country around Bellingham. Memoir of the Geological Survey of Great Britain, Sheet 13, (England and Wales).

GEORGE, T N, and 6 others. 1976. A correlation of Dinantian rocks in the British Isles. Geological Society of London Special Report, No. 7.

GLOVER, B W, HOLLOWAY, S, and YOUNG, S R. 1993. An evaluation of coalbed methane potential in Great Britain. British Geological Survey Technical Report, WA/93/24.

HARRISON, R, SCOTT, W B, and SMITH, T. 1989. A note on the distribution, levels and temperatures of minewaters in the Northumberland and Durham coalfields. Quarterly Journal of Engineering Geology, Vol. 22, 355-358.

HARRISON, R K. 1968. Petrology of the Little and Great Whin Sills in the Woodland Borehole, Co Durham. Bulletin of the Geological Survey of Great Britain, No. 28, 38-54.

HAWKES, L, and SMYTHE, J A. 1931. Garnet-bearing sands of the Northumberland coast. Geological Magazine, Vol. 68, 345-361.

HEDLEY, W P. 1931. The stratigraphy of the Bernician and Millstone Grit of south Northumberland. Transactions of the Natural History Society of Northumberland, Durham and Newcastle upon Tyne (New Series), Vol. 7, 179-190.

HEDLEY, W P, and WAITE, S T. 1929. The sequence of the Upper Limestone Group between Corbridge and Belsay. Proceedings of the University of Durham Philosophical Society, Vol. 8, 136-152.

HEMMINGWAY, J E, and TAMAR-AGHA, M Y. 1975. The effects of diagenesis on some heavy minerals from the sandstones of the Middle Limestone Group in Northumberland. Proceedings of the Yorkshire Geological Society, Vol. 40, 537-546.

HESLOP, M K, and SMYTHE, J A. 1910. On the dyke at Crookdene (Northumberland) and its relations to the Collywell, Tynemouth and Morpeth dykes. Quarterly Journal of the Geological Society of London, Vol. 66, 1-18.

HOLLIDAY, D W. 1993. Mesozoic cover over northern England: interpretation of apatite fission track data. Journal of the Geological Society of London, Vol. 150, 657-660.

HOLLIDAY, D W, BURGESS, I C, and FROST, D V. 1975. A recorrelation of the Yoredale limestones (Upper Viséan) of the Alston Block with those of the Northumberland Trough. Proceedings of the Yorkshire Geological Society, Vol. 40, 319-334.

HOLMES, A, and HARWOOD, H F. 1928. The age and composition of the Whin Sill and the related dykes of the north of England. Mineralogical Magazine, Vol. 21, 495-542.

HOLMES, A, and HARWOOD, H F. 1929. The tholeiite dykes of the north of England. Mineralogical Magazine, Vol. 22, 1-52.

HOWSE, R. 1864. Notes on the fossil remains of some recent and extinct mammalia found in the counties of Northumberland and Durham. Transactions of the Tyneside Naturalists Field Club, Vol. 15, 111-121.

HULL, J H. 1968. The Namurian stages of north-eastern England. Proceedings of the Yorkshire Geological Society, Vol. 36, 297-308.

HUTTON, W. 1832. On the stratiform basalt associated with the Carboniferous formation of the north of England. Transactions of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne, Vol. 2, 187-214.

JACKSON, I, LAWRENCE, D J D, and FROST, D V. 1985. Geological notes and local details for sheet NZ27 Cramlington, Killingworth and Wide Open (SE Northumberland), part of 1:50k sheets 14 (Morpeth) and 15 (Tynemouth). British Geological Survey Technical Report, (Unnumbered).

JOHNSON, G A L. 1958. Biostromes in the Namurian Great Limestone of Northern England. Palaeontology, Vol. 1, 30-31.

JOHNSON, G A L. 1959. The Carboniferous stratigraphy of the Roman Wall district in western Northumberland. Proceedings of the Yorkshire Geological Society, Vol. 32, 83-130.

JOHNSON, G A L. 1967. Basement control of Carboniferous sedimentation in northern England. Proceedings of the Yorkshire Geological Society, Vol. 36, 175-194.

JOHNSON, G A L. 1970. Carboniferous. 23-42 in The geology of Durham County. HICKLING, G (editor). Transactions of the Natural History Society of Northumberland, Durham and Newcastle-upon-Tyne, No. 41.

JOHNSON, G A L (editor). 1995. Robson’s geology of north east England. Transactions of the Natural History Society of Northumbria. Vol. 56, 226-391.

JOHNSON, G A L, HEARD, A J, and O’MARA, P T. 1995. Carboniferous, in Robson’s Geology of North East England (second edition). Transactions of the Natural History Society of Northumbria, Vol. 56, 226-391.

JOHNSON, G A L, HODGE, B L, and FAIRBAIRN, R A. 1962. The base of the Namurian and of the Millstone Grit in north-east England. Proceedings of the Yorkshire Geological Society, Vol. 33, 341-362.

JONES, N S. 1996. Report on the sedimentology of Namurian strata examined at selected localities on the Morpeth and Rothbury sheets. British Geological Survey Technical Report, WA/96/87R.

KIMBELL, G S, CHADWICK, R A, HOLLIDAY, D W, and WERNGREN, O C. 1989. The structure and evolution of the Northumberland Trough from new seismic reflection data and its bearing on modes of continental extension. Journal of the Geological Society, London, Vol. 146, 775-787.

LAND, D H. 1974. Geology of the Tynemouth district. Memoir of the Geological Survey of Great Britain, Sheet 15, (England and Wales).

LAWRENCE, D J D, and JACKSON, I. 1986. Geology of the Ponteland-Morpeth district. Research Report of the British Geological Survey.

LAWRENCE, D J D, and JACKSON, I. 1990a. Geology and land-use planning: Morpeth-Bedlington-Ashington. Part 1, Land-use planning. British Geological Survey Technical Report, WA/90/14.

LAWRENCE, D J D, and JACKSON, I. 1990b. Geology and land-use planning: Morpeth-Bedlington-Ashington. Part 2 Geology. British Geological Survey Technical Report, WA/90/19.

LEBOUR, G A. 1875a. On the ‘Little Limestone’ and its accompanying coal in south Northumberland. Transactions of the North of England Institute of Mining and Mechanical Engineers, Vol. 24, 73-83.

LEBOUR, G A. 1875b. On the limits of the Yoredale Series in the north of England. Geological Magazine, Vol. 2, 539.

LEBOUR, G A. 1875c. On the ‘Great’ and ‘Four-Fathom’ Limestones and their associated beds in south Northumberland. Transactions of the North of England Institute of Mining and Mechanical Engineers, Vol. 24, 133-150.

LEBOUR, G A. 1876. On the larger divisions of the Carboniferous system in Northumberland. Transactions of the North of England Institute of Mining and Mechanical Engineers, Vol. 25, 225-237.

LEBOUR, G A. 1878. Outlines of the geology of Northumberland and Durham. (1st edition). (Newcastle upon Tyne: Lambert and Co Ltd.)

LEBOUR, G A. 1885. Brief notes on the geology of Corbridge, Northumberland. Proceedings of the Berwickshire Naturalists’ Club, Vol. 10, 121-127.

LEBOUR, G A. 1886. Outlines of the geology of Northumberland and Durham. (2nd edition). (Newcastle upon Tyne: Lambert and Co Ltd.)

LEBOUR, G A. 1889. Outlines of the geology of Northumberland and Durham. (3rd edition). (Newcastle upon Tyne: Lambert and Co Ltd.)

LEEDER, M R. 1974. Origin of the Northumberland Basin. Scottish Journal of Geology, Vol. 10, 283-296.

LEEDER, M. 1975. Lower Border Group (Tournaisian) limestones from the Northumberland Basin. Scottish Journal of Geology, Vol. 11, 151-167.

LEEDER, M R. 1982. Upper Palaeozoic basins of the British Isles: Caledonide inheritance versus Hercynian plate margin processes. Journal of the Geological Society, London, Vol. 139, 479-491.

LEEDER, M R, and MCMAHON, A H. 1988. Upper Carboniferous (Silesian) basin subsidence in northern Britain. 43-52 in Sedimentation in a synorogenic basin complex: the Upper Carboniferous of northwest Europe. BESLY, B M, and KELLING, G (editors). (Glasgow and London: Blackie and Son.)

LEEDER, M R, and STRUDWICK, A S. 1987. Delta-marine interactions: a discussion of sedimentary models for Yoredale-type cyclicity in the Dinantian of northern England. 115-130 in European Dinantian Environments. MILLER, J, ADAMS, A E, and WRIGHT, V P (editors). (Chichester: John Wiley and Sons.)

LUMSDEN, G I, TULLOCH, W, HOWELLS, M F, and DAVIES, A. 1967. The geology of the neighbourhood of Langholm. Memoir of the Geological Survey, Sheet 11 (Scotland).

LUNN, A G. 1980. Quaternary. 48-60 in The geology of north east England. ROBSON, P A (editor) (Newcastle upon Tyne: Natural History Society of Northumbria).

MCKERROW, W S, and SOPER, N J. 1989. The Iapetus suture in the British Isles. Geological Magazine, Vol. 126, 1-8.

MERRICK, E. 1910. On the superficial deposits around Newcastle upon Tyne. Proceedings of the University of Durham Philosophical Society, Vol. 2, 141-152.

MERRICK, E. 1915. On the formation of the River Tyne drainage area. Geological Magazine, Vol. 52, 293-304 and 353-360.

MILLS, D A C, and HOLLIDAY, D W. 1998. Geology of the district around Newcastle upon Tyne, Gateshead and Consett. Memoir of the British Geological Survey. Sheet 20 (England and Wales).

MILLS, D A C, and HULL, J H. 1968. The Geological Survey Borehole at Woodland, Co Durham (1962). Bulletin of the Geological Survey of Great Britain, Vol. 28, 1-37.

MILLS, D A C, and HULL, J H. 1976. Geology of the country around Barnard Castle. Memoir of the Geological Survey of Great Britain, Sheet 32 (England and Wales).

MOORE, D. 1959. Role of deltas in the formation of some British Lower Carboniferous cyclothems. Journal of Geology, Vol. 67, 522-539.

NATIONAL COAL BOARD. 1965. Coal survey seam maps. (London: National Coal Board Scientific Department.)

NATIONAL COAL BOARD. 1975. Subsidence engineer’s handbook. (London: National Coal Board.)

NATIONAL COAL BOARD. 1982. The treatment of disused mine shafts and adits. (London: National Coal Board Mining Department.)

NRA. 1994. Abandoned mines and the water environment. Report of the National Rivers Authority. Water Quality Series No. 14. (London: HMSO).

NRA. 1996. Environmental assessment of selected abandoned minewaters. Report of the National Rivers Authority, Northumbria and Yorkshire Region, Leeds.

NUDDS, J R. 1977. A new species of Aulina (Rugosa) from the Namurian of northern England. Proceedings of the Yorkshire Geological Society, Vol. 41, 189-196.

OWENS, B. 1972. Palynological report on the IGS Throckley Borehole. British Geological Survey Technical Report, PDL/72/41R.

OWENS, B, and 5 others. 1977. Palynological division of the Namurian of northern England and Scotland. Proceedings of the Yorkshire Geological Society, Vol. 41, 381-398.

PEEL, R F. 1949. A study of the Northumbrian spillways. Transactions of the Institute of British Geographers, Vol. 15, 73-89.

PEEL, R F. 1956. The profiles of glacial drainage channels. Geographical Journal, Vol. 122, 483-487.

PHILLIPS, J. 1836. Illustrations of the geology of Yorkshire. Part II, The Mountain Limestone District. (London).

PIGGOT, R J, and EYNON, P. 1978. Ground movements arising from the presence of shallow abandoned mine workings. 749-780 in Large ground movements and structures. (Proceedings of conference held at the University of Wales Institute of Science and Technology, Cardiff, 1977) GEDDES, J D (editor) (London: Pentech Press).

RAISTRICK, A. 1931. Glaciation. 281-291 in The geology of Northumberland and Durham. CARRUTHERS, R G (editor), Proceedings of the Geologists’ Association, Vol. 42.

RAMSBOTTOM, W H C. 1973. Transgressions and regressions in the Dinantian: a new synthesis of British Dinantian stratigraphy. Proceedings of the Yorkshire Geological Society, Vol. 39, 567-607.

RAMSBOTTOM, W H C. 1977. Major cycles of transgression and regression (mesothems) in the Namurian. Proceedings of the Yorkshire Geological Society, Vol. 41, 261-291.

RAMSBOTTOM, W H C, and 6 others. 1978. A correlation of Silesian rocks in the British Isles. Geological Society of London, Special Report, No. 10.

RANDALL, B A O. 1959. Intrusive phenomena of the Whin Sill, east of the R North Tyne. Geological Magazine, Vol. 96, 385-392.

RANDALL, B A O. 1980a. The Great Whin Sill and its associated dyke suite. 67-75 in The geology of north-east England.

ROBSON, D A (editor). (Newcastle upon Tyne: Natural History Society of Northumbria.)

RANDALL, B A O. 1980b. The Tertiary dykes. 75-77 in The geology of north-east England. ROBSON, D A (editor). (Newcastle upon Tyne: Natural History Society of Northumbria.)

RICHARDSON, G. 1965. Summary of Progress of the Geological Survey of Great Britain for 1964. (London: HMSO.)

RICHARDSON, G. 1966. Summary of Progress of the Geological Survey of Great Britain for 1965. (London: HMSO.)

RICHARDSON, G, and FRANCIS, E H. 1971. Fragmental clayrock (FCR) in coal-bearing sequences in Scotland and north-east England. Proceedings of the Yorkshire Geological Society, Vol. 38, 229-260.

RILEY, N J. 1998a. Fauna associated with the Great Limestone Mootlaw Quarry, Ryall Matfen, Northumberland. British Geological Survey Technical Report, WH/98/26R.

RILEY, N. 1998b. Notes on ammonoids collected by A Pringle from the Great Limestone, Mootlaw Quarry, Ryal, Matfen, Northumberland. British Geological Survey Technical Report (Stratigraphy Series), WH/98/41R.

ROBINS, N S and YOUNGER, P L. 1996. Coal abandonment mine water in surface and near-surface environment: some historical evidence from the United Kingdom. Proceedings of the Mining, Metals and the Environment II conference, Prague, Czechoslovakia, 3-6 September 1996, Institute of Mining and Metallurgy, London, 253-262.

ROBSON, D A (editor) 1980. The geology of north-east England (Newcastle upon Tyne: Natural History Society of Northumbria).

SEDGWICK, A. 1827. On the association of trap rocks with the Mountain Limestone Formation of High Teesdale etc. Transactions of the Cambridge Philosophical Society, Vol. 2, 139-195.

SHIELLS, K A G. 1964. The geological structure of north-east Northumberland. Transactions of the Royal Society of Edinburgh: Earth Sciences, Vol. 95, 449-484.

SISSONS, J B. 1958. Subglacial stream erosion in southern Northumberland. Scottish Geographical Magazine, Vol. 74, 163-174.

SISSONS, J B. 1960. Erosion surfaces, cyclic slopes and drainage systems in southern Scotland and northern England. Transactions of the Institute of British Geographers, Vol. 28, 23-38.

SLADEN, J A. 1979. Weathering and its effect on the geotechnical properties of tills in south-east Northumberland. Unpublished MSc thesis, University of Newcastle upon Tyne.

SMITH, S. 1912. Report of the committee appointed to report upon the Carboniferous Limestone Formation of the north of England with special reference to its coal resources. (Newcastle upon Tyne: North of England Institute of Mining and Mechanical Engineers.)

SMITH, S. 1923. Lead and zinc ores of Northumberland and Alston Moor. Special Report on the Mineral Resources of Great Britain, Memoir of the Geological Survey of Great Britain, Vol. 25.

SMYTHE, J A. 1908. Glacial phenomena of the country between the Tyne and the Wansbeck. Transactions of the Natural History Society of Northumberland, Vol. 3, 141-157.

SMYTHE, J A. 1912. Glacial geology of Northumberland. Transactions of the Natural History Society of Northumberland, Vol. 4, 86-116.

SMYTHE, J A. 1930. A chemical study of the Whin Sill. Transactions of the Natural History Society of Northumberland, Vol. 7, 16-150.

SOPER, N J, ENGLAND, R W, SNYDER, D B, and RYAN, P D. 1992. The Iapetus suture zone in England, Scotland and eastern Ireland: a reconciliation of geological and deep seismic data. Journal of the Geological Society of London, Vol. 149, 697-700.

TATE, G. 1870. The basaltic rocks of Northumberland. Transactions of the Berwickshire Naturalists Club, Vol. 6, 197-217.

TAYLOR, B J, BURGESS, I C, LAND D H, MILLS D A C, SMITH, D B, and WARREN, P T. 1971. British Regional Geology: Northern England (4th edition) (London: HMSO for Institute of Geological Sciences).

TEALL, J J H. 1884a. Petrological notes on some north-of England dykes. Quarterly Journal of the Geological Society of London, Vol. 40, 209-247.

TEALL, J J H. 1884b. On the chemical and microscopical characters of the Whin Sill. Quarterly Journal of the Geological Society of London, Vol. 40, 640-657.

TEALL, J J H. 1888. British petrography with special reference to the igneous rocks. (London: Dulau and Co.)

TEALL, J J H. 1889. On the amygdaloids of the Tynemouth dyke. Geological Magazine, Vol. 6, 481-483.

THABET, K M A. 1973. Geotechnical properties and sedimentation characteristics of tills in south-east Northumberland. Unpublished PhD thesis (2 vols), University of Newcastle upon Tyne.

TOMKIEFF, S I. 1929. A contribution to the petrology of the Whin Sill. Mineralogical Magazine, Vol. 22, 100-120.

TOMKIEFF, S I. 1953. The tholeiite dyke at Cowgate, Newcastle upon Tyne. Proceedings of the University of Durham Philosophical Society, Vol. 11, 91-94.

TOPLEY, W, and LEBOUR, G A. 1877. On the intrusive character of the Whin Sill of Northumberland. Quarterly Journal of the Geological Society of London, Vol. 33, 406-422.

TRADE AND INDUSTRY COMMITTEE. 1995-96. Former Mineshafts. (House of Commons 7th Report). (London: HMSO.)

TROTTER, F M, and HOLLINGWORTH, S E. 1927. On the Upper Limestone Group and ‘Millstone Grit’ of north-east Cumberland. Summary of Progress of the Geological Survey of Great Britain for 1926, 98-107.

WOOLACOT, D. 1905. The superficial deposits and pre-glacial valleys of the Northumberland and Durham coalfields. Quarterly Journal of the Geological Society of London, Vol. 61, 64-95.

WOOLACOT, D. 1921. The interglacial problem and the glacial and post-glacial sequence in Northumberland and Durham. Geological Magazine, Vol. 58, 21-32 and 60-69.

YOUNG, B. 1998. The Liddesdale Group of 1:50 000 scale Sheet 14 (Morpeth): lithostratigraphy and local details. British Geological Survey Technical Report, WA/98/09.

YOUNG, B, and LAWRENCE, D J D. 1998. The Morpeth Group of 1:50 000 scale Sheet 14 (Morpeth): lithostratigraphy and local details. British Geological Survey Technical Report, WA/98/10.

YOUNGER, P L. 1993. Possible environment impact of the closure of two collieries in County Durham. Journal of the Institute of Water and Environmental Management, Vol. 7, 521-531.

YOUNGER, P L. 1994. Minewater pollution: The revenge of Old King Coal. Geoscientist, Vol. 4, 6-8.

YOUNGER, P L. 1995a. Minewater pollution in Britain: Past present and future. Mineral Planning, Vol. 65, 38-41.

YOUNGER, P L. 1995b. Hydrogeochemistry of minewaters flowing from abandoned coal workings in the Durham coalfield. Quarterly Journal of Engineering Geology, Vol. 28, 101-103.

YOUNGER, P L. 1998. Coalfield abandonment: Geochemical processes and hydrochemical products. 1-29 in The Environmental Geochemistry of Energy Resources. NICHOLSON, K (editor). Society of Environmental Geochemistry and Health, MacGregor Science, Aberdeen.

YOUNGER, P L. 1997. The longevity of minewater pollution: a basis for decision-making. The Sciences of the Total Environment, Vol, 194/195, 457-466

Figures, plates and tables

Figures

(Figure 1) Geological map of the Morpeth district.

(Figure 2) Topography of the district.

(Figure 3) Interpreted depth (below Ordnance Datum) to the top of the Caledonian basement in the district (after Chadwick et al., 1995). Contour interval 200 m

(Figure 4) Image of aeromagnetic data for the western part of the district. P1 to P3, T1 to T5, F1, M W (see text for details). Illumination from the north-west.

(Figure 5) Stratigraphy of the upper part of the Liddesdale Group: generalised succession, nomenclature and classification.

(Figure 6) Stratigraphy of the Stainmore Group: generalised succession, nomenclature and classification.

(Figure 7) Outcrop of Shaftoe Grits, Stainmore Group.

(Figure 8) Diagrammatic section through Shaftoe Grits, Stainmore Group.

(Figure 9) Stratigraphy of the Coal Measures: generalised succession, nomenclature and classification.

(Figure 10) Structural features of the district.

(Figure 11) Buried channels in the eastern part of the district. Depth to rockhead is given in metres.

Plates

(Front cover) Cover photographThe imposing crenellated tower of Belsay Castle [NZ 0848 7855] is one of the finest surviving examples of a medieval border tower house. Adjoining it on the left is the roofless ruin of the Jacobean manor house. Both the castle and manor house are built of a medium-grained sandstone, quarried locally from a thick sandstone unit that overlies the Corbridge (Lower Felltop) Limestone of Namurian age (D5174). (Photographer T S Bain.)

(Plate 1) Synclinal fold in Great Limestone overlain by undeformed mudstones, Mootlaw Quarry [NZ 0227 7537] (D5168).

(Plate 2) Sandstone between Corbridge and Thornborough limestones, Quarry Gardens, Belsay Hall [NZ 0840 7840] (D5175).

(Plate 3) Shaftoe Grits at Shaftoe Crags [NZ 0515 8163] (D5170).

(Plate 4) Brenkley Opencast Coal Site [NZ 206 750] (D3623).

(Plate 5) Down Hill, a large glacially transported raft of Great Limestone [NZ 0030 6851] (L1979).

(Plate 6) Subsidence hollows above old pillar and stall workings, Brenkley [NZ 208 752] (D3729).

(Back cover)

Tables

(Table 1) Geological succession in the Morpeth district

(Table 2) Nomenclature and classification of Carboniferous rocks at outcrop in the Morpeth district. The Great Limestone was included in the uppermost part of the Middle Limestone Group on the previous (1955) edition of Sheet 14 Morpeth, although Fowler (1936) took the Great Limestone as the lowest unit of the Upper Limestone Group in the Rothbury district.

(Table 3) Distinctive elements in the Namurian marine macrofaunas of Northumberland. 1 Great Limestone; 2 Little Limestone; 3 Belsay Dene Limestone; 4 Corbridge Limestone; 5 Pike Hill Limestone; 6 Thornborough Limestone; 7 Newton Limestone; 8 marine bands between the Newton and Dalton Limestones; 9 Dalton Limestone; 10 limestone group above the Dalton Limestone; 11 marine band group below the ‘Subcrenatum (Quarterburn) Marine Band’. *relatively numerous records. †relatively few records. The Pernopecten sp. nov. is the form, so far undescribed, found within associated strata of the Orchard and Calmy limestones in Scotland. The former is regarded as being of E2a age. Equally, Dibunophyllum cf. linnense and Leptagonia smithi? have been recorded from exposures in the Thornborough Limestone in the adjacent Newcastle upon Tyne district (Sheet 20). These forms are recorded from the Orchard and Calmy limestones in Scotland and appear to be confined to E2 there.

(Table 4) Characteristic nonmarine faunas of the Coal Measures of the district. Nonmarine bivalve zones (and stratigraphic limits): Anthraconaia lenisulcata (base ‘Subcrenatum (Quarterburn). Marine Band’ to Ganister Clay Coal) no nonmarine faunas known. 1. Carbonicola communis (Ganister Clay to Top Busty coals). 2. Anthraconaia modiolaris (Top Busty to Top Bensham coals). 3. Lower Anthracosia similis-Anthraconaia pulchra (Top Bensham Coal to base Aegiranum (Ryhope) Marine Band). 4. Upper Anthracosia similis-Anthraconaia pulchra (base Aegiranum (Ryhope) to top Cambriense (Down Hill) marine bands) only known from above the West Moor Coal.

(Table 5) Fossils of the Westphalian marine bands of the district. 1 ‘Subcrenatum (Quarterburn)’; 2 ?Honley; 3 ?Listeri (Kay’s Lea); 4 Amaliae (Gubeon); 5 Well Hill; 6 Stobswood; 7 Vanderbeckei (Harvey); 8 Maltby (High Main); 9 ?Clown (Ryhope Little); 10 Haughton (Kirkby’s); 11 Sutton (Hylton); 12 Aegiranum (Ryhope)

(Table 6) Coal seams of Coal Measures in the Morpeth district.

(Table 7) Sustainable yields of water from boreholes in the district

(Table 8) Typical groundwater quality from selected boreholes in the Morpeth district. n/d - not determined.

Tables

(Table 3) Distinctive elements in the Namurian marine macrofaunas of Northumberland

1 Great Limestone; 2 Little Limestone; 3 Belsay Dene Limestone; 4 Corbridge Limestone; 5 Pike Hill Limestone; 6 Thornborough Limestone; 7 Newton Limestone; 8 marine bands between the Newton and Dalton Limestones; 9 Dalton Limestone; 10 limestone group above the Dalton Limestone; 11 marine band group below the ‘Subcrenatum (Quarterburn) Marine Band’.

(Table 4) Characteristic nonmarine faunas of the Coal Measures of the district

Nonmarine bivalve zones (and stratigraphic limits): Anthraconaia lenisulcata (base ‘Subcrenatum (Quarterburn). Marine Band’ to Ganister Clay Coal) no nonmarine faunas known. 1. Carbonicola communis (Ganister Clay to Top Busty coals). 2. Anthraconaia modiolaris (Top Busty to Top Bensham coals). 3. Lower Anthracosia similis-Anthraconaia pulchra (Top Bensham Coal to base Aegiranum (Ryhope) Marine Band). 4. Upper Anthracosia similis-Anthraconaia pulchra (base Aegiranum (Ryhope) to top Cambriense (Down Hill) marine bands) only known from above the West Moor Coal.

(Table 5) Fossils of the Westphalian marine bands of the district.

1 ‘Subcrenatum (Quarterburn)’; 2 ?Honley; 3 ?Listeri (Kay’s Lea); 4 Amaliae (Gubeon); 5 Well Hill; 6 Stobswood; 7 Vanderbeckei (Harvey); 8 Maltby (High Main); 9 ?Clown (Ryhope Little); 10 Haughton (Kirkby’s); 11 Sutton (Hylton); 12 Aegiranum (Ryhope)

(Table 6) Coal seams of Coal Measures in the Morpeth district.

(Table 7) Sustainable yields of water from boreholes in the district

(Table 8) Typical groundwater quality from selected boreholes in the Morpeth district. n/d - not determined.