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The geology of the Wenlock Edge area (explanation of 1:25 000 geological sheet SO59)

By B. A. Hains

Bibliographic reference: 1970. The geology of the Wenlock Edge area (explanation of 1:25 000 geological sheet SO59). London, HMSO [for the Institute of Geological Sciences].

Natural Environment Research Council. The Institute of Geological Sciences was formed by the incorporation of the Geological Survey of Great Britain and the Museum of Practical Geology with Overseas Geological Surveys and is a constituent body of the Natural Environment Research Council.

The geology of the Wenlock Edge area (explanation of 1:25 000 geological sheet SO59) by B. A. Hains, B.Sc., Ph.D.

London Her Majesty's Stationery Office 1970. © Crown copyright 1970. SBN 11 880125 2.

(Front cover) Cover picture: View of Hope Dale, between the Wenlock and Aymestry escarpments

Preface

The 1:25 000 sheet of the Wenlock Edge area is one of a number of such sheets which are being produced by the Institute of Geological Sciences for selected areas of Great Britain. It shows all the topographical detail available on the larger six-inches to one mile (1:63 360) maps, at which scale the area was surveyed, and it carries contours at 25 ft (7.6 m) intervals. In complex areas details of the geology can be delineated in greater detail than is possible on the one-inch to one mile (1:63 360) maps.

Wenlock Edge lies to the east of the well-known Church Stretton area (Sheet SO49). These two maps, together with that of Craven Arms (Sheet SO48) to the south, cover one of the geologically most interesting areas in the country.

The present account is designed to be read in conjunction with the map, to which the reader is referred. Extensive use has been made of the co-ordinates of the National Grid in defining the position of localities.

K. C. Dunham, Director, Institute of Geological Sciences, Exhibition Road South Kensington London SW7, 21st August 1970

Chapter 1 Introduction

The area shown on 1:25 000 Geological Sheet SO59 lies in the southern part of the county of Shropshire, in the quiet hill-country of the Welsh Borders. There are no towns or villages of any size within the area, and agriculture remains the basic occupation of the inhabitants. Almost the only industry is the limestone quarrying on the northern part of Wenlock Edge.

Topographically the area is dominated by the N.E.–S.W. strike of most of the rocks. In the north-west corner the northeasterly trending Uriconian ridge of Lawley, lying within the Church Stretton Fault Complex, separates areas of low ground occupied by softer Carboniferous and Cambrian rocks. To the south-east are the steep escarpments of Hoar Edge and Yell Bank, both rising to more than 1000 ft (300 m) O.D. They are formed by the Ordovician Hoar Edge Grit and Chatwall Sandstone respectively and are separated by the broad Ruckley and Langley valley floored by Harnage Shales. Between Church Preen [SO 542 981] and Cardington [SO 506 952] there are a number of gently rounded ridges formed by sandstones within the Acton Scott Group, and south of Cardington Uriconian rocks give rise to the high ground of Hill End and Stoneacton.

The south-eastern half of the area is marked by a series of scarps and dales which are formed by hard and soft beds within a south-easterly dipping series of Silurian and Old Red Sandstone sediments. The scarps are formed by the Wenlock Limestone and Tickwood Beds (Wenlock Edge), the Aymestry Group, and the sandstones at the base of the Ditton Series, with the complementary valleys of Ape Dale, Hope Dale and Corve Dale floored by the softer Wenlock Shales, Lower Ludlow Shales and Ledbury Group. Wenlock Edge is a long continuous scarp which maintains a height of around 750 to 900 ft (230–275 m) whereas the Aymestry Group ridge, also around 900 ft (275 m) high, is divided into a number of separate hills by steep-sided south-easterly trending valleys.

The southern half of the area is drained by the Eaton Brook and River Corve and their tributaries which flow southwards towards the River Teme. The northern part is drained by the Hughley Brook and smaller streams such as the Bentleyford Brook which flow northwards to join the River Severn.

Geological history

The succession of geological formations in the area is shown in the vertical sections on either side of the map. The solid rocks range in age from Pre-Cambrian (probably more than 700 million years old) to Upper Coal Measures (about 295 million years old). Over much of the area they are obscured by superficial deposits of various types which were laid down during Pleistocene and Recent times (approximately during the last 2 million years). In some cases formations are separated by unconformities representing periods of time in which earth movements and erosion took place.

The oldest rocks are the Uriconian volcanics of Lawley, Hill End and Stoneacton. In the adjacent Church Stretton area they are succeeded by Longmyndian sediments. Strong folding and denudation preceded the deposition of the Cambrian sediments which crop out south-east of Lawley and in an isolated area at Hill End. The basal beds are quartzites, laid down in a shallow current-swept sea, succeeded by shallow-water glauconitic sandstones. These Lower Cambrian beds were folded and differentially eroded before the deposition of the Middle Cambrian shales and sandstones. Steady subsidence followed in Upper Cambrian times with the deposition of a considerable thickness of mud, and the Cambrian Period was ended by widespread uplift with some minor folding.

During Ordovician and Silurian times, sedimentation in the Welsh Borders was dominated by two major palaeogeographical features, the relatively stable Midland shelf area to the east and the Welsh Geosyncline to the west. There is a contrast in fades between the geosyncline, where subsidence was fairly continuous and rapid with the deposition of shales and greywackes, and the shelf, where subsidence was slower and a thinner sequence of sandstones, mudstones and limestones was laid down. Only a small part of the Ordovician sequence, the Caradoc Series, is represented in the Wenlock Edge area where it comprises shelf-facies sediments–sandstones and siltstones with an abundant shelly fauna. West of the Long Mynd, in the Shelve district, a full pre-Caradoc sequence is present. Folding and denudation took place at the end of the Ordovician Period, and the highest Ordovician (Ashgill Series) and lowest Silurian rocks are absent. In Middle and Upper Llandovery times there was an eastward transgression of the sea from the Welsh Geosyncline, and near-shore grits and conglomerates were laid down around the southeastern margin of the Long Mynd and in the Church Preen–Kenley district. These beds are succeeded and overlapped by the shallow-water siltstones and limestones of the Pentamerus Beds and the mudstones of the Hughley Shales. During Wenlock and Ludlow times the broad boundary zone between the shelf and the geosyncline appears to have lain in the general region of the Church Stretton Fault Complex. The sediments laid down in the Wenlock Edge area were siltstones, silty mudstones and limestones, largely of the shelf facies. At the close of the Silurian Period earth-movements caused the gradual elevation of the geosynclinal sediments in Wales into a folded mountain chain, and this caused the conversion of the shelf sea of Ludlow times into a subsiding delta plain. The consequent transition from a marine to a continental environment is seen in the sediments of the Downton Series of the Lower Old Red Sandstone. There is a long gap in the local sedimentary record between the Ditton Series of the Lower Old Red Sandstone and the Coed-yr-Allt Beds of the Leebotwood Coalfield. These rocks, of Upper Coal Measures age, are shales, sandstones and thin coals which were the result of rhythmic deltaic sedimentation such as characterized much of the deposition of the Coal Measures in other parts of Britain.

There is a further long gap in the local sedimentary record between the Coed-yr-Allt Beds (about 295 million years old) and the superficial deposits of Pleistocene times (up to about 2 million years old). During the latter period the Wenlock Edge area was invaded by ice from the Shropshire Plain to the north and, to a much smaller extent, from the Welsh hills to the west. The glacial deposits, which are largely boulder clay, provide evidence for only one period of glaciation.

Chapter 2 Pre-Cambrian: Uriconian

Uriconian rocks occur in two small areas; both are on the western margin of the map and are the eastern extremities of outcrops which lie mainly within the Church Stretton area to the west (Wright 1968). The northern area lies within the Church Stretton Fault Complex and forms the north-eastern part of the Lawley [SO 502 986] while the southern area around Hill End and Stoneacton [SO 507 937] is the eastern end of the Cardington Hill outcrop.

The Uriconian rocks are dominantly volcanic in origin and consist mainly of tuffs (consolidated volcanic ash) and various types of lava including basalt, andesite, dacite and rhyolite. Intrusive masses of quartz-porphyry and dolerite are present in the southern area. It is not possible to correlate the strati-graphical sequences in the two areas and they are therefore considered separately.

The Lawley

This area of Uriconian rocks is bounded to the north-west by the Church Stretton. Fault (F1). On the south-eastern slopes of Lawley the Uriconian is overlain unconformably by the Cambrian Wrekin Quartzite, but farther to the north-east the southern boundary of the outcrop is the Lawley Fault (F2).

The rocks of this area have been described by Robertson (in Pocock and others 1938, pp. 27–30). On Lawley itself they appear to have a steep south-easterly dip. The lowest beds, on the north-western slopes of the hill, are basic tuffs at least 100 ft (30 m) thick consisting of large and small fragments of various types of lava. They are succeeded by about too ft (30 m) of rhyolitic lavas and tuffs, the lavas commonly being strongly brecciated. These beds are overlain by 30 to 40 ft (9–12 m) of rhyolite (shown separately on the map) which forms conspicuous pinkish grey crags in two areas on the ridge and eastern side of the hill. The rhyolite is overlain, in the southern corner of the area, by further lavas and tuffs ranging from acid to basic in composition.

At the north-eastern end of Lawley there is a section in the Lawley Brook [SO 5063 9914] which displays an anticline in fine and coarse-grained tuffs. Farther north, the narrow strip of Uriconian rocks between F1 and F2 consists mainly of acid tuffs and rhyolites. Brecciated rhyolite is exposed in the Bentleyford Brook [SO 5079 9925].

Cardington Hill

The Cardington Hill area of Uriconian rocks is limited to the north by the Sharpstones Thrust and to the south by an unconformable cover of Ordovician and Silurian sediments. Immediately to the north, a faulted inlier of Uriconian quartz-porphyry forms the high ground of Hill End and is overlain to the east by the Cambrian Wrekin Quartzite. The lowest beds are thought to be the Stoneacton Tuffs and Andesites, of unknown thickness. They are separated from the overlying North Hill Dacites, about 900 ft (275 m) thick, by an intrusion of quartz-porphyry. The highest beds within the Wenlock Edge area are the Middle Hill Andesites and Dacites. All the divisions are poorly exposed.

Stoneacton Tuffs and Andesites

This group has a limited outcrop at the eastern end of the Cardington Hill area, west of Gilberries. It includes dark greenish grey tuffs with green lithic fragments and light brown gritty beds with pink rhyolite fragments. In the Heath Brook [SO 5122 9371] there is a small development of andesite. The outcrop is limited to the west by an intrusion of quartz-porphyry.

North Hill Dacites

The outcrop of the North Hill Dacites, to the west of Stoneacton, is cut by intrusive quartz-porphyry. The rocks are fine-grained and pink or purple and grey in colour, leached to pale pink or white where weathered.

Middle Hill Andesites and Dacites

This group has a very small outcrop on the western margin of the area. There are no exposures in this area, but to the west on Middle Hill [SO 492 939] (Wright 1968) porphyritic and non-porphyritic lavas are seen.

Intrusions

The main intrusion of this area is the quartz-porphyry which occupies the eastern end of Cardington Hill and underlies the Cambrian rocks of Hill End. Exposures are few and the mapping is dependent largely on scattered rock fragments. The rock is pink with a granular groundmass of quartz, albiteoligoclase and orthoclase and corroded phenocrysts of quartz, sericitized albite-oligoclase, orthoclase and biotite. Chlorite may replace original amphibole. Close to the junction with the Stoneacton Tuffs and Andesites there are exposures of mottled pink and green quartz-microdiorite, possibly a separate intrusion.

A narrow dolerite dyke cuts the quartz-porphyry to the north-west of Stoneacton [SO 5052 9387].

Chapter 3 Cambrian

There are two separate outcrops of Cambrian rocks within the Wenlock Edge area. The southern outcrop lies to the east of Hill End [SO 505 944], near Cardington, where the beds have a general south-easterly or east-south-easterly dip. They are bounded to the south by the Hill End and Sharpstones thrusts; to the west they rest unconformably on Uriconian quartz-porphyry and to the east are overlain unconformably by the Pentamerus Beds. The second outcrop, largely obscured by boulder clay, occupies the low ground between the Uriconian mass of Lawley [SO 503 986] and the scarp of Hoar Edge [SO 504 974] and Lodge Hill [SO 5195 9940] formed by the Ordovician Hoar Edge Grit. The strata have a variable south-easterly dip and are continuous with those of the classic Comley area to the west (Wright 1968). The sequences in the two areas appear to be similar but detailed comparison is not possible because of the lack of exposure.

Lower Cambrian

Wrekin Quartzite

The Wrekin Quartzite is a white or pale grey fine-grained quartzite, locally sugary in appearance, and sometimes stained yellow or brown. Coarser grained beds occur locally, especially towards the base of the formation. Since it is a basement bed resting on an uneven surface its thickness is rather variable; it appears to be up to about 100 ft (30 m) thick in both the Lawley and Hill End areas.

At Hill End the Quartzite forms a prominent south-westerly trending strike ridge which swings to E.–W. at its southern end, near the Sharpstones Thrust. Sixty feet (18 m) of beds are seen in an old quarry [SO 5070 9450] about 550 yd (500 m) S.W. of Mill Farm, Cardington, and there are crags of quartzite along the ridge to the south.

On Lawley the Wrekin Quartzite extends along the eastern slopes of the hill, where it rests unconformably on the Uriconian. It is not well exposed but there are abundant quartzite fragments in the soil. It appears to be faulted against the Lower Comley Series (Lower Comley Sandstone) to the south-east by the Lawley Fault (F2) (p. 49).

Lower Comley Series

The Lower Comley Series is poorly exposed within the Wenlock Edge area. In the Comley district (Cobbold 1927; Wright 1968) to the west it is divided into two formations; the Lower Comley Sandstone, a greenish grey glauconitic sandstone about 500 ft (150 m) thick, is at the base, with the fossiliferous Lower Comley Limestones, up to 6 ft (2 m) thick, above.

At Hill End the Lower Comley Sandstone is not exposed, though fragments of green glauconitic sandstone are present in the soil to the east of the Wrekin Quartzite ridge.

North-east of Lawley the Lower Comley Sandstone is seen in a road section [SO 5058 9900] some 800 yd (730 m) to the west of Coppice House and also in the Bentleyford Brook [SO 5082 9921] about 350 yd (320 m) farther to the north-east.

There is no evidence of the presence of the Lower Comley Limestones in the Wenlock Edge area, and they may have been cut out by the unconformity at the base of the overlying Upper Comley Series.

Middle Cambrian

Upper Comley Series

The Upper Comley Series is very poorly exposed within the Wenlock Edge area. Farther west, around Comley, it consists of a series of conglomerates, breccias, sandstones and shales probably between 300 ft (90 m) and 600 ft (180 m) thick which rest unconformably on the Lower Cambrian. The Comley area has been described in detail by Cobbold (1927), Greig and others (1968) and Wright (1968).

There are no exposures of the Upper Comley Series at Hill End; its outcrop is presumed to lie to the south-east of that of the Lower Comley Sandstone.

South-east of Lawley the outcrop of the Upper Comley Series is almost entirely obscured by boulder clay. Sandstone, probably of Upper Comley Series age, is exposed in the brook [SO 5081 9888] 530 yd (485 m) W. of Coppice House. An excavated section (Stubblefield 1930, pp. 56–7) in the Bentleyford Brook [SO 5114 9948] showed thin-bedded glauconitic sandstones with a Middle Cambrian fauna overlain by grey shales of Upper Cambrian age. As Uriconian rocks occur some 50 yd (46 m) to the north of this section, it appears that the Middle Cambrian is faulted against the Uriconian by the Lawley Fault (F2).

Upper Cambrian

The soft, easily weathered Upper Cambrian shales occupy the low-lying ground at the eastern end of the Hill End area and most of the broad hollow between Lawley and Hoar Edge. They have been divided into the following sequence:

Because of the general lack of exposures it is not possible to map out these subdivisions and they are shown on the geological maps as one group.

Neither the Grey (Orusia) Shales nor the Black Shales are exposed in the Hill End area.

An excavated section in the Bentleyford Brook [SO 5114 9947]–[SO 5117 9946] (Stubblefield 1930, pp. 56–8), parts of which are still visible, gave a continuous exposure through the Grey and Black shales. The sequence starts with about 63 ft (19 m) of grey micaceous shales (the Grey Shales), with some calcareous concretions, which have yielded the brachiopod Orusia lenticularis (Wahlenberg). These beds are overlain by a one-inch bed of fine-grained brown sandstone succeeded by about 13 ft (4 m) of black shales (the Black Shales) with numerous black bituminous limestone concretions or 'stinkstones' which in some cases contain trilobites including Ctenopyge flagellifera (Angelin). There appears to be a slight non-sequence between the Black Shales and the overlying Shineton Shales. The Grey Shales are also seen in a brook [SO 5095 9909] some 480 yd (440 m) to the south-west.

The Tremadoc Shineton Shales are exposed at intervals in the Heath Brook [SO 5122 9447]–[SO 5120 9389] for about 0.5 mile (0.8 km) S. of the Mill, Cardington. They are mainly green or greyish green shales with an east-south-easterly dip of 20 to 45 degrees, and contain a fauna including the brachiopods Acrotreta sabrinae (Callaway) and Lingulella nicholsoni Callaway, the trilobites Shumardia curta Stubblefield and Dichelepyge phylax Hutchison and Ingham and the graptolites Clonograptus tenellus (Linnarsson) and Dictyonema flabelliforme (Eichwald). An abortive attempt to sink a shaft, presumably for coal, was made in 1911 on the west bank of the brook [SO 5119 9445].

North-west of Lawley the Shineton Shales are seen above the Black Shales in the Bentleyford Brook (see above), and there are some poor exposures along the north-western side of Hoar Edge, beneath the Hoar Edge Grit, which have yielded the graptolite Dictyonema flabelliforme.

Chapter 4 Ordovician: Caradoc Series

Ordovician rocks occupy a broad area between the Cambrian rocks to the south-east of Lawley and the Uriconian and Cambrian rocks of Hill End. To the east their outcrop is limited by the overstep of the basal Silurian. They have a general south-easterly dip which is about 50 to 70 degrees in the basal beds on Hoar Edge decreasing south-eastwards to 10 to 20 degrees in the highest beds around Plaish and Cardington. Another, small, area of Ordovician rocks lies to the north of Wall Bank between the Uriconian. of Stoneacton and the basal Silurian. This area is the eastern extremity of an outcrop which extends south-westwards to Marshbrook and the Onny Valley (Sheet SO48).

The succession in the vertical section on the map shows that only part of the Ordovician, the Caradoc Series, occurs in the Wenlock Edge area. In the Shelve area, west of the Long Mynd, the Arenig, Llanvirn and Llandeilo series underlie the Caradoc while in other parts of the country the Ashgill Series lies above it. It consists predominantly of shallow-water sandstones and siltstones with a shelly fauna, chiefly brachiopods and trilobites, locally so abundant as to form thin limestones. These sediments were probably laid down in a shelf area which was relatively stable and was not submerged until Caradoc times, in contrast to the more rapidly subsiding basin which extended into Wales from west of the Long Mynd, and in which deposition took place throughout the earlier part of the Ordovician Period.

Subdivisions of the shaly rocks of the basin facies are based on graptolite faunas, the zones recognized in the Caradoc Series of Wales being those of Nemagraptus gracilis, Diplograptus multidens, Dicranograptus clingani and Pleurograptus linearis in upward succession. The shelf facies of the Wenlock Edge area has a predominantly shelly fauna, but some graptolites have been found which enable a partial correlation to be made with the succession in the basin area to the west. Dean (1958, pp. 226–30) discussed the correlation of the shelly and graptolite faunas and concluded that all the beds above the Chatwall Flags could probably be assigned to the D. clingani Zone and that there was no acceptable evidence of the presence of the P. linearis Zone in south Shropshire.

The palaeontological classification of the Caradoc Series is based on the work of Bancroft who developed a system dependent on his recognition of a succession of distinctive brachiopod–trilobite faunas. Dean (1958) amplified this work and made a new correlation between the shelly and graptolite faunas. The lithological classification used in the present account follows that of Greig and others (1968). Although some of the lithological units used are diachronous, in so far as they are units they constitute a classification which is useful to the layman and the geologist in the field. (Figure 1) shows the relation of the palaeontological classification to Dean's lithological units and those used in this account; it is based largely on Dean's work (1958, figs. 3 and 4; 1960, fig. 2; in Whittard 1955–67, fig. 10).

Hoar Edge Grit

The Hoar Edge Grit forms the prominent escarpment of Hoar Edge [SO 504 974] and Lodge Hill [SO 519 994]. It rests unconformably on the Cambrian Shineton Shales which occupy the broad hollow to the north-west of Hoar Edge. From Hoar Edge to a minor fault on the south side of Lodge Hill the Grit has a south-easterly dip of 50 to 70 degrees, but to the north of this fault the dip is more variable. North of Lodge Hill the escarpment terminates against the southern end of the Coundmoor Fault (Pocock and others 1938, p. 175). The outcrop of the Grit continues north of the fault, but is partly obscured by boulder clay.

On Hoar Edge the Grit is about 400 ft (120 m) thick and consists of pale grey or white medium to coarse-grained sandstones, locally feldspathic, with pebbly beds near the base. Most of the pebbles are of quartz but igneous fragments, probably of Uriconian origin, also occur. Exposure is poor, though there are some old quarries [SO 509 979] about 700 yd (640 m) N.W. of Chatwall Hall which show medium and coarse-grained sandstones. From Lodge Hill northwards towards Harnage [SJ 566 043] and Evenwood [SJ 556 015], north of the present area, the Grit thins progressively and passes laterally into calcareous sandstones with shelly beds. The most southerly exposures of these calcareous beds are on Lodge Hill where there are small sections about 400 yd (365 m) S. [SO 5174 9950] and 550 yd (500 m) S.S.E. [SO 5193 9936] of Frodesley Lodge. The former locality has yielded a shelly fauna including Favositid corals, brachiopods including Dinorthis jiabellulum (J. de C. Sowerby), bivalves, gastropods and trilobites.

In the Harnage–Cressage area north of the map Dean (1958, pp. 198–9) has recognized a threefold subdivision of the Grit:

• Rhynchonellid Grits
• Sandy limestones with Harknessella subquadrata Bancroft
• Sandy shales and limestones with Harknessella subplicata Bancroft

He pointed out that the Rhynchonellid Grits are Harnagian and that the fauna of the underlying beds (with H. subquadrata) shows certain Harnagian elements. This led him to the conclusion that no important break occurs at about this level in the Caradoc Series, as postulated by Robertson (in Pocock and others 1938, p. 86). The zonal graptolite Nemagraptus gracilis (Hall) has been recorded from the sandy shales and limestones with H. subplicata.

The Hoar Edge Grit is not present in the area of Caradoc Series rocks north of Wall Bank [SO 504 930], and here the Harnage Shales rest directly on the Uriconian.

Harnage Shales

There are three separate outcrops of Harnage Shales within the Wenlock Edge area. The southernmost outcrop [SO 503 932] is situated just north of Wall Bank, and there is a small area of probable Harnage Shales which lies to the west of Hill End.

The third and largest outcrop occupies the hollow between Hoar Edge and Yell Bank [SO 506 970] and extends northeastwards to cover a broad area between Lodgehill Coppice [SO 523 995] and Parkgate [SO 553 997]. It is largely covered by boulder clay. In general the Shales are soft and easily weathered and are poorly exposed even where there is no drift cover.

In the outcrop to the north of Wall Bank the Harnage Shales rest unconformably on the Uriconian rocks of Cardington Hill and at the western margin of the area are overlain by the Chatwall Flags. To the east they are rapidly overstepped by the unconformable basal Silurian (Pentamerus Beds). They are about 300 to 400 ft (90–120 m) thick and consist mainly of grey and brown shales and mudstones with a southeasterly dip of about 20 degrees. Calcareous pebbly grits and sandstones occur locally at the base and thin beds of grit and flags at higher levels. Greenish grey striped silty shales with the trilobite Reuscholithus reuschi Bancroft occur in the stream [SO 5029 9309] north of Wall Bank, and similar beds with the trilobites Broeggerolithus cf. harnagensis (Bancroft), Reuscholithus reuschi and Salterolithus sp. and the ostracods Primitia sp., Tallinnella sp.and Ulrichia bicornis (Jones) are seen in the stream [SO 4967 9301] just to the west of the present area.

To the west of Hill End the presence of a fault-bounded outcrop of Harnage Shales has been inferred from the occurrence at [SO 4994 9431], just to the west of the present area, of green shelly sandstone with a fauna probably belonging to the Chatwall Flags (p. 17).

In the main, northern outcrop the Shales are probably at least 1000 ft (300 m) thick, comprising grey and greenish mudstones with beds of sandstone and some calcareous beds. They occupy the broad hollow between the ridges formed by the Hoar Edge Grit and the Chatwall Flags and Sandstone. North of Mereoak [SO 548 991] they are overlain unconformably by the basal Silurian (Kenley Grit). The outcrop is almost entirely covered by boulder clay and there are only a few poor exposures in the topmost beds of the Shales. A section in the road [SO 5112 9746] west of Chatwall Farm has yielded various species of the graptolite genera Climacograptus and Orthograptus.

Chatwall Flags

The southernmost outcrop of the Chatwall Flags lies at the western margin of the area [SO 500 929] west of Wall Bank. It is cut out to the east by the overstep of the basal Silurian (Pentamerus Beds). There is a further small area [SO 500 943] of probable Chatwall Flags to the west of Hill End. In these southerly outcrops the beds are mainly brown or green fine-grained flags and are commonly crinoidal. The main outcrop of the Chatwall Flags lies on the upper part of the northerly facing Chatwall Sandstone scarp. It extends north-northeastwards along Yell Bank [SO 508 971] through Chatwall to the southern part of Netherwood Coppice and is overstepped by the basal Silurian (Kenley Grit) just south of Mereoak [SO 548 991]. The Flags have a south-easterly dip of about 50 degrees from Enchmarsh to Chatwall but farther to the east the dip decreases to 20 degrees in a south-south-easterly direction. In this northern area they comprise yellow flaggy sandstones and sandy mudstones with lenses of impure limestone and beds of crinoid columnals, and are up to 300 ft (90 m) thick.

In the small outcrop west of Wall Bank the only exposure is in a track section [SO 5006 9292] where brown siltstone with crinoid ossicles is seen.

To the west of Hill End there are no sections within the Wenlock Edge area. Immediately to the west, however, there is a small exposure [SO 4994 9431] of green shelly sandstone, dipping at 20 degrees to the west, which has yielded a poorly preserved fauna including the brachiopod Onniella cf. soudleyensis (Bancroft) and the trilobites Broeggerolithus cf. broeggeri (Bancroft) and B. cf. soudleyensis (Bancroft). These fossils indicate that the beds should probably be included within the Chatwall Flags.

At the western end of the main outcrop of the Chatwall Flags crinoidal flaggy sandstone near the base of the formation is seen in the lane [SO 5016 9671] about 350 yd (320 m) N. of Enchmarsh. The type area for the Chatwall Flags and Sandstone, around Chatwall Hall [SO 515 975], has recently been described by Dean (1960). Dark greyish green flaggy sandstones with occasional mudstones, near the base of the formation, are seen in the roadside [SO 5128 9752] north-north-west of Chatwall Farm. These beds contain abundant columnals of the crinoid Balacrinus [Glyptocrinus]aff. basalis (McCoy) and graptolites including Climacograptus sp.and Orthograptus truncatus (Lapworth). Higher beds of similar lithology occur in the quarry [SO 5137 9758] 150 yd (137 m) N.E. of Chatwall Farm and contain (according to Dean 1960, p. ,67) an extensive shelly fauna including the trilobites Broeggerolithus cf. broeggeri and Brongniartella cf. minor (Salter) and the brachiopods Macrocoelia expansa (J. de C. Sowerby) and Sowerbyella soudleyensis Jones. Both faunas are of Soudleyan age (Figure 1). Farther east along the outcrop of the Flags there are a few small sections in similar beds.

Chatwall Sandstone

The Chatwall Sandstone caps the scarp which extends northeastwards from Enchmarsh through Chatwall to Netherwood Coppice. It is overstepped by the unconformable basal Silurian (Kenley Grit) about 500 yd (460 m) N. of Church Preen. The Sandstone dips to the south-east at 40 to 60 degrees from Enchmarsh to Lower Chatwall [SO 520 980], but farther east the strike swings to east-north-east. It is a greenish grey and purple argillaceous sandstone, weathering to yellow, with beds containing small pebbles of quartz, quartzite and grit and occasional beds of shale. Its thickness has been estimated to be 300 ft (go m) on Yell Bank (Mitchell in Greig and others 1968, p. 129) and 100 to 120 ft (30–37 m) to the east of Chatwall (Pocock and others 1938, p. 81). Dean (1960), however, would restrict it to only 26 ft (7.9 m) of beds at Chatwall (see below).

The only good sections in the Sandstone are in the vicinity of Enchmarsh and at Chatwall. Green, purplish and yellow sandstones with some pebble beds are exposed at many places within the hamlet of Enchmarsh and along the road towards Chatwall. At Chatwall, the road cutting [SO 5136 9744] east of Chatwall Farm has been described in detail by Dean (1960, p. 166) and may be summarized as follows:

His study of the faunas from this section showed that the three groups of beds could be assigned to the stages indicated, and also that the highest and lowest zones of the Lower Longvillian were absent. These faunal breaks, together with the changes in lithology at the top and base of the Lower Longvillian beds, led him to conclude that non-sequences occur both above and below the rocks of that stage (Figure 1). Finally he suggested that the name Chatwall Sandstone should be applied only to the 26 ft (7.9 m) of Lower Longvillian beds, those above and below being assigned to the alternata Limestone and Chatwall Flags respectively. The fauna within the 26 ft of Lower Longvillian beds includes the brachiopods Dalmanella lepta (Bancroft) and Sowerbyella soudleyensis and the trilobites Broeggerolithus cf. globiceps (Bancroft) and Brongniartella cf. minor. In Pocock and others (1938, pp. 87–8) the alternata Limestone is included within the Chatwall Group but it is not clear at what precise horizon within the section the base of the limestone was taken. The base of the Chatwall Sandstone was taken, on lithological criteria, at an horizon apparently some 80 to 90 ft (24–27 m) below that suggested by Dean.

alternata Limestone

The crop of the alternata Limestone adjoins that of the underlying Chatwall Sandstone. It has not been mapped separately east of a point [SO 5332 9828] about 1100 yd (1000 m) W. of Church Preen, and here it has been included with the Cheney Longville Flags. The Limestone consists of a succession of lenticular shelly limestones up to 2 ft (0.6 m) thick which are characterized by the abundance of the brachiopod Heterorthis alternata (J. de C. Sowerby) and are interbedded with green micaceous flags and shales. Its thickness is uncertain, but is probably not greater than about 40 ft (12 m).

The best section in the Limestone is at Chatwall, in the southern part of the road cutting [SO 5136 9744] described above (p. 18). about 35 ft (10.7 m) of beds are visible, comprising yellow massive and flaggy sandstones with many beds of weathered sandy limestone. Apart from H. alternata, the fauna (Dean 1960, p. 168) includes the brachiopods Bancroftina robusta (Bancroft), Kjaerina bipartita (Salter), Sowerbyella sericea (J. de C. Sowerby) and Strophomena grandis (J. de C. Sowerby) and the trilobites Broeggerolithus longiceps (Bancroft), Brongniartella bisulcata (McCoy) and Kloucekia apiculata (McCoy). The outcrop of the Limestone can be traced from fragments in the soil and it is exposed in the farmyard at Broome [SO 5260 9813].

Although Bancroft's (1933) choice of the alternata Limestone as the lowest member of the Upper Longvillian Stage may have been founded on his recognition in places of a non-sequence at its base, the faunal lists published by Dean (1958, pp. 220–2) show that, in addition, the fauna of the alternata Limestone has more in common with that of the beds above than with that of the Lower Longvillian. Consequently the Limestone is now grouped with the Cheney Longville Flags rather than with the Chatwall Sandstone which was the practice adopted by Pocock and others (1938).

Cheney Longville Flags

The Cheney Longville Flags have a broad outcrop which extends from the western margin of the area [SO 500 960] south of Enchmarsh east-north-eastwards towards Church Preen [SO 544 982] where they are overstepped by the unconformable basal Silurian (Kenley Grit). They have a variable south-easterly dip, and form the greater part of the dip slope to the south-east of the Chatwall Sandstone scarp. The southeastern part of this slope is partly obscured by drift.

Together with the alternata Limestone, the Flags make up the Upper Longvillian and Marshbrookian stages of Bancroft (Figure 1). They comprise yellowish weathering greenish grey flags with interbedded shales and rubbly siltstones. Thin beds of fine-grained sandstone occur and thin Shelly limestones, usually decalcified, are quite common. Brachiopods and trilobites are common throughout the formation and amongst other fossils which occur, the most conspicuous and characteristic is Tentaculites. The Flags are probably about 600 ft (180 m) thick.

There is a number of small sections in the Flags, mainly in the lower part of the formation. The most westerly sections are in the old lanes below Enchmarsh. Shelly flags [SO 5032 9639] 200 yd (180 m) E. of the hamlet contain an Upper Longvillian fauna which includes the brachiopods Bancroftina cf. robusta, Kjaerina geniculata Bancroft and Sowerbyella sericea, the gastropod Cyrtolites nodosus (Salter) and the trilobite Brongniartella bisulcata. Other small sections in the lower part of the Flags occur in a ditch [SO 5157 9738] south-east of Chatwall Hall and at Broome [SO 5256 9806]. Beds near the top of the formation are poorly exposed [SO 5328 9800] about 500 yd (460 m) W. of High Fields and have yielded a Marshbrookian fauna including the brachiopods Dalmanella cf. unguis (J. de C. Sowerby) and Schizocrania crassa (Salter non Hall) and the trilobites Primaspis cf. caractaci (Salter) and Chasmops extensa (Boeck).

Acton Scott Group

The Acton Scott Group has an extensive triangular outcrop around Cardington [SO 506 952], Gretton [SO 515 953] and Plaish [SO 530 963]. To the south it terminates against the Hill End Thrust and to the east it is overstepped by the unconformable basal Silurian (Pentamerus Beds and Kenley Grit). Much of the outcrop is obscured by boulder clay and morainic drift. The strata have a general south-easterly dip of about io to 20 degrees.

The group is about 400 to 500 ft (120–150 m) thick and consists mainly of poorly exposed yellow and fawn mudstones or shales with two thick yellow flaggy sandstones which form conspicuous features.

The basal beds occupy the low ground at the foot of the dip slope of the Cheney Longville Flags. They are thought to be mainly shales but are very poorly exposed so that little is known of them, and their thickness, possibly 300 ft (90 m), is only an estimate.

The lower sandstone, about 50 ft (15 m) thick, runs through the village of Cardington and yellow sandstone is seen [SO 5049 9520] in front of Cardington vicarage. This section has yielded the brachiopods Hedstroemina robusta Bancroft and Leptaena salopiensis Williams. The sandstone continues north-eastwards to about 400 yd (365 m) from Cardington church where it is displaced to the east for some 300 yd (275 m) by an E.–W. fault. North of the fault the sandstone feature dies out some 300 yd (275 m) N. [SO 5204 9702] of Plaish Park.

The overlying shales are about 60 ft (18 m) thick and occupy a slack between the two sandstones. About 2 ft (0.6 m) of micaceous shaly mudstone with calcareous beds are exposed beneath drift in the lane [SO 5138 9590] about 550 yd (5130 m) S.E. of Leyhill.

The upper sandstone is about 75 ft (23 m) thick. It extends north-north-eastwards from the Hill End Thrust [SO 505 946] to an E.–W. fault north-west of Gretton. North of the fault, which displaces the sandstone to the east, it has a very broad outcrop due to its long dip slope. Much of the outcrop is drift covered, but abundant fragments of yellow sandstone in the fields [SO 5170 9630] north-west of Plaishpark Cottages contain a fauna including the brachiopods Leptaena salopiensis and Reuschella bilobata (J. de C. Sowerby) and the trilobite Primaspis caractaci (Salter).

The highest beds in the Group occur between Cardington Mill [SO 5124 9456] and Plaish. They are drift covered, the only exposure being in the brook, 30 yd (27 m) S. of Cardington Mill, where earthy grey mudstones have yielded the trilobite Tretaspis ceriodes favus Dean which suggests a high horizon in the Acton Scott Group.

Chapter 5 Silurian

Silurian rocks occupy more than half of the Wenlock Edge area. They have a broad continuous outcrop which extends diagonally across the area from south-west to north-east. Their classification is shown in detail on the side margin of the map. To the north-west they rest unconformably on Pre-Cambrian, Cambrian and Ordovician rocks and to the south-east are overlain conformably by the Old Red Sandstone. The upper limit of the Silurian System has been taken at the base of the Ludlow Bone Bed. There is a general south-easterly dip of about to degrees, apart from local variations close to faults.

The Silurian rocks of the Wenlock Edge area are part of a continuous outcrop which extends south-westwards from the Much Wenlock district to Craven Arms, Ludlow and beyond. It is known as the Main Outcrop to distinguish it from the Western Outcrop which lies on the western side of the Church Stretton Fault Complex. The rocks of the two outcrops differ considerably in facies at some horizons.

In Silurian, as in Ordovician, times southern Shropshire was situated marginally between a relatively stable shelf area to the east and an intermittently subsiding basin to the west. The boundary between the two areas lay in the general region of the Church Stretton Fault Complex, but it must be considered as a diffuse zone rather than as a sharp boundary exactly along the line of the Complex. During Llandovery times there was a gradual eastward spread of the sea from the basin area on to the shelf. The basal Silurian in the northern part of the Wenlock Edge area, the Kenley Grit, exhibits a near-shore facies with sandstones and conglomerates; farther south the lowest beds, the Pentamerus Beds, are of finer grain comprising siltstones and mudstones. By the close of Llandovery times the sediments were of uniformly fine grain over the whole area. Although classified on the map as Upper Llandovery Series, it is possible that the Kenley Grit, or part of it, may be of Middle Llandovery age (Ziegler and others 1968). The Pentamerus Beds of the Western Outcrop, adjacent to the Long Mynd, have recently been shown to be partly of Middle Llandovery age (Cocks and Rickards 1969, p. 217).

The earliest obvious difference in facies between the shelf and basin sediments occurs in the upper part of the Wenlock Series. There is a marked contrast between the shallow-water reef limestones of Wenlock Edge and the graptolitic shales of the same age in the Long Mountain area about 20 miles (32 km) to the west-north-west. Whittard (1952, pp. 170–1) and Dineley (1960, pp. 101–2) considered that the facies change takes place across the Church Stretton Fault Complex, but later work (Dean 1964, p. 285; Greig and others 1968, pp. 143–4) indicates that the westward change of facies, south of the Long Mynd, is more gradual.

The distribution of sedimentary facies in the Ludlow Series of the Welsh Borders was discussed by Holland and Lawson (1963) who concluded that the margin between the shelf and the basin facies was not as straight as the line of the Church Stretton Fault Complex but was curved and convex to the east. In addition the position of the boundary fluctuated considerably in Ludlow times. In the Upper Ludlow rocks there is no distinction between shelf and basin facies although the thickness of the sediments (calcareous shelly siltstone) increases towards the west. This uniformity in the highest Silurian rocks heralds the great palaeogeographical changes which were to follow in the Old Red Sandstone Period.

Upper Llandovery Series

Salter and Aveline (1854) proposed a threefold division of the Upper Llandovery Series (their 'Pentamerus beds') of the Main Outcrop. These subdivisions, with variations in the names, were adopted by Whittard (1925, 1928) and Pocock and others (1938) as shown in the following table:

The terminology adopted by Pocock and others has been followed in the present account. All these subdivisions are present in the northern part of the area, but south of Plaish the Kenley Grit is cut out by the overlap of the Pentamerus Beds.

Kenley Grit

The Kenley Grit extends from the northern edge of the area [SO 557 999] to a place [SO 526 952] about 1250 yd (1140 m) E. of Gretton where it is overlapped by the Pentamerus Beds. It has a south-easterly dip of 10 to 20 degrees and rests unconformably on various subdivisions of the Caradoc Series. The junction with the overlying Pentamerus Beds is everywhere obscured by boulder clay. The formation comprises yellowish brown coarse-grained sandstones, grits and conglomerates. It is probably about 150 ft (45 m) thick in the extreme north, thinning steadily southwards. North of Church Preen it gives rise to a well-marked ridge.

There are only a few poorly exposed sections in the Kenley Grit. Grits and conglomerates are seen in old quarries [SO 531 961] north of Sheaves Farm and on the dip slope [SO 535 968] 200 to 400 yd (180–365 m) N. of Holt. There are several sections around Church Preen, and an old quarry [SO 5414 9784] 400 yd (365 m) S.S.W. of the church shows about to ft (3 m) of irregularly alternating beds of coarse and fine-grained grit with strong vertical jointing.

No fossils have been recorded from the Kenley Grit of the Wenlock Edge area, but Lingula spp.and other brachiopods occur farther to the north. Recent work by Ziegler and others (1968, fig. it) suggests that the Kenley Grit, or part of it, may be of Middle Llandovery age.

pentamerus Beds

The crop of the Pentamerus Beds extends from south of Wall Bank [SO 500 925] to the northern limit of the area [SO 575 999]. North-east of Heath Brook [SO 511 935] it is almost entirely obscured by boulder clay. The Pentamerus Beds rest unconformably on Pre-Cambrian, Cambrian and Ordovician rocks south of Oak Wood [SO 526 951] and overlie the Kenley Grit to the north. They are succeeded by the Hughley Shales to the southeast.Their thickness is estimated to be about 150 ft (45 m) in the south, increasing to perhaps 350 ft (105 m) in the north. The formation comprises grey shaly siltstones and silty mudstones with many sandy laminae. Pale grey sandy limestones and fine- to medium-grained calcareous sandstone beds, usually less than 3 in (75 mm) thick but occasionally as much as 1 ft (0.3 m) in thickness, are common. The characteristic brachiopod Pentamerus oblongus J. de C. Sowerby is abundant in most of the limestones and locally in the siltstones.

Grey shales with shelly beds are exposed in the Coley Brook [SO 5050 9286] near Wall Bank, but the best section in the Pentamerus Beds in the Wenlock Edge area is in the Heath Brook [SO 5116 9361]–[SO 511 2 9344] south-west of Gilberries. The beds here are grey mudstones and siltstones with beds of hard shelly limestone which have a general dip to the south-east of i o to 19 degrees. As well as P. oblongus and other brachiopods this section has yielded (Whittard 1928, pp. 741, 746) the graptolite Glyptograptus aff. tamariscus (Nicholson).

An interesting section occurs in the Bentleyford Brook [SO 5086 9934] about 700 yd (640 m) N.W. of Coppice House, on the north-west side of the Church Stretton Fault (F1). Sandy mudstones with calcareous beds and lenses, locally much veined with calcite, crop out in the stream. The beds are unfossiliferous, though numerous loose blocks of Pentamerus Beds limestone occur in the stream bed. Robertson (in Pocock and others 1938) considers that the outcrops are probably Pentamerus Beds whereas Whittard (1932, pp. 865–6) suggests that they are of Carboniferous age and that the blocks of Pentamerus Beds limestone have been derived from elsewhere.

Hughley Shales

This formation, equivalent to the Purple Shales of Whittard, takes its name from the hamlet of Hughley [SO 565 980] in the northern part of the area, below Wenlock Edge. Its outcrop, which lies to the south-east of that of the Pentamerus Beds and is largely obscured by boulder clay, extends from the western edge of the area [SO 500 920] near Hargrove Wood through Wall under Heywood and Hughley to the northern limit of the map. The Shales comprise purple and maroon shaly mudstones, locally silty, with many green bands and patches. Thin calcareous laminae are common and thin beds of shelly and argillaceous limestone occur locally. They are 200 to 250 ft (60–75 m) thick in the south and may thin northwards to about 150 ft (45 m).

Sections in the Hughley Shales are confined to the Heath Brook, north of Wall under Heywood, and the Hughley Brook and its tributaries around and to the north-east of Hughley. Greenish grey and purple micaceous mudstones with hard green silty beds are seen in the Heath Brook [SO 5112 9338] about 600 yd (550 m) S.W. of Gilberries. South-west of Hughley, alternating beds of grey to purple shale and grey fine-grained sandstone, with graptolites including Monograptus marri Perner, are seen in a tributary [SO 5622 9764] of the Hughley Brook. These beds are perhaps one-third of the way from the top of the Shales. From Hughley northwards the upper beds of the formation are well exposed and the boundary between the Hughley and Wenlock shales crosses the Hughley Brook several times. The strata are purple and green mottled mudstones with thin beds of shelly limestone containing brachiopods including Costistricklandia lirata (J. de C. Sowerby) and Eocoelia sulcata (Prouty) (Ziegler and others 1968, p. 749). The junction with the overlying Wenlock Shales is seen in a tributary [SO 5745 9904] about 950 yd (870 m) to the east of New Hall where there is an upward passage from predominantly purple mudstone to predominantly bluish grey mudstone within 2 ft (0.6 m).

Wenlock Series

The subdivision of the Wenlock Series adopted in the present account is essentially lithological and is the same as that in the Church Stretton Memoir (Greig and others 1968). It differs in several respects from that adopted by Pocock and others (1938) for the Shrewsbury District although that publication deals with the northern part of the present area. The two classifications are as follows:

The Wenlock Shales are largely drift covered and it has not proved possible to trace separately the Coalbrookdale and Buildwas beds. Cocks and Rickards (1969, pp. 228–9) suggest that the Coalbrookdale Beds, when traced southwards from the type area at Buildwas [SJ 640 046], progressively overlap first the Buildwas Beds and then successively older horizons in the Hughley Shales until they rest directly on the Ordovician near Craven Arms (Sheet SO48). The overlying Tickwood Beds comprise a transition zone between the Wenlock Shales and Wenlock Limestone.

The Wenlock Limestone as interpreted by Pocock and others (1938) can be subdivided into two lithological units within the northern part of the area. These comprise nodular limestones and siltstones (of Tickwood Beds lithology) with sporadic masses of reef-limestone (Wenlock Limestone Reef Facies) overlain by flaggy crystalline crinoidal limestone (Wenlock Limestone). Traced southwards the reef limestones die out west of Easthope [SO 5596 9532] and south of this place the Wenlock Limestone rests directly on the Tickwood Beds. The flaggy crinoidal limestones pass laterally southwards into bedded crystalline limestones and finally into bedded nodular limestones (p. 35 and (Figure 2)).

Wenlock Shales

This formation has a broad continuous outcrop from the south-west corner to the north-east corner of the area. It occupies the lower slopes of Wenlock Edge and much of the broad vale to the north-west. The greater part of the outcrop is obscured by boulder clay and head. The Shales, which have a general south-easterly dip of about so degrees, overlie the Hughley Shales to the north-west and are overlain by the Tickwood Beds.

The Wenlock Shales are 900 to 1000 ft (275–305 m) thick. They comprise flaggy and shaly grey siltstones and silty mudstones, locally calcareous, with thin nodular argillaceous limestone beds in the upper part and calcareous nodules and bullions towards the base. There is an upward transition into the Tickwood Beds, but this is not always continuous and between Easthope Wood [SO 561 957] and Lower Hill Farm [SO 584 978] there is a development of nodular limestones of Tickwood Beds facies within the upper part of the Shales. Fossils, particularly brachiopods and trilobites, are common throughout the sequence, and the lowest beds (the Buildwas Beds) are typified by a large number of small fossils, particularly brachiopods.

Because of the extensive drift cover, sections in the Wenlock Shales are largely confined to the upper part of the formation, on the slopes of Wenlock Edge. There are, however, some exposures in the basal beds in the Hughley Brook.

An excellent section occurs in a small stream [SO 5138 9147]–[SO 5171 9123] 410 yd (375 m) S. of Rushbury church and for 450 yd (410 m) towards the south-east. About 235 ft (72 m) of beds are intermittently exposed, consisting of pale greenish grey, flaggy, silty mudstones with very occasional calcareous beds and beds of calcareous nodules. Similar beds are seen in the stream on the south-east side of the village, and were exposed in trenches along the road between the village and the station. These sections have yielded a very large fauna including the brachiopods Aegiria [Chonetoidea] grayi (Davidson), Craniops implicata (J. de C. Sowerby), Plectodonta cf. transversalis (Wahlenberg), Resserella cf. elegantula (Dalman) and Skenidioides lewisii (Davidson), the trilobites Calymene nodulosa Shirley and Dalmanites caudatus (Brünnich), the ostracod Beyrichia kloedeni McCoy and the graptolites Monograptus cf. dubius (Suess), M. cf. flemingii (Salter) and M. cf. priodon (Bronn). Greenish grey shales with limestone bullions up to 8 in (0.2 m) in diameter, near the base of the Wenlock Shales, crop out in the stream [SO 5244 9371] north-west of East Wall.

The nodular limestone of Tickwood Beds facies within the Wenlock Shales between Easthope Wood and Lower Hill Farm is exposed in the lane [SO 5631 9585] east-south-east of Wood Farm and in the old railway cutting [SO 5698 9662] south-south-east of Upper Hill Farm. It is also seen in the old railway cutting [SO 5741 9706] about 700 yd (670 m) W. of Presthope Farm where some 25 to 30 ft (7.6–9.1 m) of bedded silty mudstones with nodular limestone beds and argillaceous limestone nodules pass upwards and downwards into less calcareous beds.

The basal beds of the Wenlock Shales are seen in numerous sections in the Hughley Brook and its tributaries between Brook House [SO 554 972] and the northern edge of the area. They comprise grey mudstones with beds of silty limestone nodules and an abundant fauna of broken trilobites and small brachiopods. Beds of white bentonitic clay occur locally as, for example, in stream sections [SO 5622 9733] 840 yd (770 m) E.8°N. of Brook House and [SO 5751 9895] 1000 yd (915 m) E 12°S. of New Hall.

Tickwood Beds

The crop of the Tickwood Beds extends north-eastwards from the southern margin of the area at Stars Coppice [SO 505 900] to Blakeway Coppice [SO 6000 9925] north of Stretton Westwood. It is affected by several minor dip faults between Stars Coppice and Hilltop [SO 568 963]. The Tickwood Beds overlie the Wenlock Shales and are overlain by the Wenlock Limestone south of Easthope Wood [SO 5596 9532] and the Wenlock Limestone Reef Facies to the north. They occupy the upper part of the scarp slope of Wenlock Edge and have a general southeasterly dip of about to degrees.

The Tickwood Beds comprise alternating beds of grey fine-grained argillaceous limestone and grey calcareous siltstone. The limestone beds are generally tabular in form although in the northern part of the crop around Presthope they become more nodular. The limestone beds are usually 1 to 3 in (25–75 mm) thick and in the main part of the formation make up about 50 per cent of the rock. Towards the base of the formation the siltstones become progressively more dominant and there is a passage into the Wenlock Shales beneath. South of Easthope Wood there is a rapid upward transition into the Wenlock Limestone. To the north-east, where the Tickwood Beds are succeeded by the Reef Facies, the top of the formation is less clearly defined owing to the lateral, though spasmodic, development of reefs in strata of Tickwood Beds lithology. The formation is at least 140 ft (40 m) thick in the south, but decreases to about 50 ft (15 m) in thickness north-east of Hilltop mainly as a result of the facies change in the upper part due to the inclusion of reefs.

Despite their position on the scarp face of Wenlock Edge the Tickwood Beds are not particularly well exposed. The base and top of the formation are closely defined in track sections south of Stars Coppice, partly within the present area. In the track [SO 5037 8997] 400 yd (365 m) E.8°S. of Eaton Rectory, 4 ft (1.2 m) of calcareous and silty mudstone with occasional limestone nodules (Wenlock Shales) are overlain by about 12 ft (3.7 m) of interbedded mudstone and fine-grained limestone (Tickwood Beds). Here, the Tickwood Beds contain the brachiopods Brachyprion fletcheri (Davidson), Howellella elegans (Muir-Wood) and Leangella segmentum (Lindström). In the same track, at the top of the scarp [SO 5056 9008], there are further exposures of interbedded mudstone and limestone. The junction with the overlying Wenlock Limestone must be in the 7 ft (2.1 m) of unexposed beds between this section and a quarry in the Limestone on the scarp crest. The Tickwood Beds may be as much as 180 ft (55 m) thick here. There is a good section in a road cutting [SO 5396 9264] 650 yd (595 m) S.S.E. of Wilderhope which shows 50 to 55 ft (15–17 m) of alternating mudstone and limestone beds, and similar beds in an old quarry [SO 5491 9383] about 400 yd (365 m) W. of Pilgrim Cottage have yielded the brachiopods 'Camarotoechia' nucula (J. de C. Sowerby) and 'Chonetes' minimus (J. de C. Sowerby) and the ostracod Hemsiella [Beyrichia] maccoyiana (T. R. Jones). Another road cutting [SO 5524 9442] some 600 yd (550 m) W.N.W. of Murder Pool shows the transition from the Tickwood Beds to the Wenlock Limestone. Farther north, at the western end [SO 5806 9743] of Presthope tunnel (Robertson in Pocock and others 1938, p. 113), there is an atypical development of the Beds, with a rapid downward transition from bedded nodular limestone with 'ballstones' (Wenlock Limestone Reef Facies) into bedded nodular limestone and silty mudstone (Tickwood Beds). About 50 ft (15 m) of Tick-wood Beds are exposed, and although the proportions of limestone and mudstone are approximately equal they are not evenly bedded as in typical Tickwood Beds.

Wenlock Limestone reef facies

The outcrop of the Wenlock Limestone Reef Facies extends north-eastwards from Easthope Wood [SO 55 96] along the crest of Wenlock Edge to the eastern limit of the area [SO 600 990] north of Stretton Westwood. An up-faulted area of the formation lies to the east of Wenlock Edge, between Easthope and Hilltop Farm [SO 571 963]. The Reef Facies is about 90 ft (27 m) thick at Presthope, but from Hilltop southwards it thins rapidly and dies out within half a mile (0.8 km).

The Wenlock Limestone Reef Facies consists of flat-bottomed lenticular masses of reef limestone ('ballstone') up to 80 ft (24 m) in thickness surrounded by bedded nodular limestone with siltstone beds. The surrounding strata, similar in lithology to the Tickwood Beds, arch over and sometimes sag beneath the 'ballstones', probably as a result of differential compaction. The 'hailstones' consist largely of the skeletons of reef-forming organisms, particularly corals and stromatoporoids, commonly in the position of growth and set in a matrix of bluish grey and green calcite-mudstone. Crosfield and Johnston (1914) concluded that they were formed under conditions similar to those behind a barrier reef or in a lagoon. They also concluded that, since the surrounding strata contain a large coral fauna identical to that in the 'ballstones' but not in the position of growth, the 'ballstones' underwent partial destruction by wave action before final burial.

The most southerly exposure of the Reef Facies on Wenlock Edge is immediately below the road [SO 5615 9553] 680 yd (620 m) W.28°N. of Easthope church where small 'ballstone' masses up to 3 ft (0.9 m) in diameter occur within strata of Tickwood Beds facies. North-eastwards for about half a mile (0.8 km) from a small valley [SO 5692 9640] in the scarp face north-west of Hilltop Farm, the top of the scarp is formed by a discontinuous line of cliffs up to 40 ft (12 m) high. The cliffs are largely formed by 'ballstone' masses and locally, as at Major's Leap [SO 5696 9646], the 'ballstones' can be seen to rest on bedded nodular limestone with calcareous mudstone partings which sags beneath them.

The disused Lilleshall Quarry presents an excellent section in the Reef Facies. The main face of the quarry [SO 5738 9676] shows large 'ballstone' masses with bedded nodular limestone with shale films and partings dipping off them. At the base of the face there are about 6 ft (1.8 m) of nodular limsetone interbedded with mudstone. In the north-eastern and southeastern parts of the quarry the Wenlock Limestone (p. 35) is seen above the Reef Facies and just to the south-east of the main face a narrow strip [SO 5744 9674] of Wenlock Limestone and Lower Ludlow Shales is let down between two sub-parallel faults. The extensive fauna from this quarry is typical of the Reef Facies and includes the hydrozoan Labechia conferta (Lonsdale), the corals Coenites sp., Favosites gothlandicus forma forbesi Milne Edwards and Haime and Heliolites interstinctus (Linné), the brachiopods Atrypa reticularis (Linné), Dolerorthis rustica (J. de C. Sowerby), Eospirifer plicatellus interlineatus (J. de C. Sowerby) and Leptaena rhomboidalis (Wilckens) and the gastropod Poleumita globosa (Schlotheim).

North-east of Presthope there are numerous disused and working quarries on the dip slope displaying extensive sections in both the Reef Facies and the overlying Wenlock Limestone.

In the faulted outcrop north of Easthope, 'balllstones' are visible in Easthope village [SO 5668 9530] and in old quarries [SO 5716 9630] to the east of Hilltop Farm.

Wenlock Limestone

The crop of the Wenlock Limestone extends from Oldfield Coppice [SO 900 510] in the south to the eastern limit of the area [SO 600 988] north of Stretton Westwood. An up-faulted area of the Limestone lies to the north of Easthope. As well as the faults at Easthope, the southern part of the outcrop is affected by a number of minor dip faults. The Limestone is about 20 to 25 ft (6–7.5 m) thick in the north, thickening to 30 ft (9 m) and locally to 50 ft (15 m) S. of Easthope. Despite its comparative thinness it has a broad outcrop on the dip slope of Wenlock Edge, particularly in the southern part of the area. In general the dip is south-easterly at about 10 degrees.

In the south the Wenlock Limestone is a roughly bedded, nodular, finely crystalline, argillaceous limestone with thin siltstone beds and partings. The best section in these beds is at Roman Bank [SO 5206 9102] where 15 ft (4.5 m) of limestone are exposed. A persistent limestone bed 4 ft (1.2 m) from the top of the section shows a slight development of chert. There is a lateral change in the vicinity of Wenlock Edge School [SO 557 947] to a more evenly bedded, sometimes flaggy, nodular crystalline limestone, and a further lateral change to a flaggy crinoidal limestone takes place between the north end of Easthope Wood [SO 562 956] and Hilltop [SO 570 963] (Figure 2). Sections in the north-east part of Lilleshall Quarry [SO 5762 9686] show about 15 ft (4.5 m) of flaggy crystalline crinoidal limestone, locally with pink mottling, passing down into the Reef Facies which here consists of bedded nodular limestone with silty mudstone films and partings. A pavement of crystalline limestone with large ripple marks is seen in the old quarry [SO 5808 9726] north of Presthope Farm. Old quarries to the north-west of Stretton Westwood show upwards of 15 ft (4.6 m) of flaggy and massive crinoidal limestone overlying the Reef Facies.

In the faulted outcrop of Wenlock Limestone north of Easthope flaggy crystalline limestone is exposed in old workings [SO 5687 9579] in Limekiln Rough and about 12 ft (3–7 m) of bedded, crystalline, crinoidal limestone occur in an old quarry [SO 5737 9639] 400 yd (365 m) E.N.E. of Hilltop Farm.

Ludlow Series

As a result of recent work, particularly in the type area around Ludlow, a re-classification of the Ludlow Series, based mainly on faunal assemblages, has been put forward by Holland, Lawson and Walmsley (1959, 1963). It has been possible to some extent to tie in their biostratigraphical classification with the lithological classification used in the present account (Figure 4).

Shergold and Shirley (1968) have published an account and map of the Ludlow Series beds between Craven Arms and Bourton using a slightly modified form of Holland, Lawson and Walmsley's classification.

The upper and lower limits of the Ludlow Series have been taken at the base of the Ludlow Bone Bed and the top of the Wenlock Limestone respectively. The base of the calcareous Aymestry Group is transitional and appears to lie within the Lower Bringewood Beds. Farther south-west, around Craven Arms (Haim 1969), the whole of the Lower Bringewood Beds have been included in the Lower Ludlow Shales. The upper limit of the Aymestry Group appears to coincide with the top of the Basal Upper Leintwardine Beds of Shergold and Shirley (1968).

Lower Ludlow Shales

The outcrop of the Lower Ludlow Shales extends from the southern limit of the area at Blackwood Farm [SO 520 900] to the eastern limit [SO 600 985] near Stretton Westwood. They occupy most of the scarp slope below the Aymestry Group and also floor the long strike valley of Hope Dale. The strata have a general south-easterly dip of between 8 and 14 degrees.

The Shales are about 600 ft (180 m) thick throughout their outcrop, and show little lateral variation in lithology. The basal 100 ft (30 m) of beds comprise olive-green and grey siltstones, with layers of fine-grained limestone nodules particularly in the lower part where there is a rapid upward transition from the Wenlock Limestone. These beds commonly have a speckled appearance owing to an abundance of small shell fragments and are equivalent to the Lower Elton Beds of Holland, Lawson and Walmsley (1959). The main part of the Shales, about 400 ft (120 m) thick, is equivalent to the Middle and Upper Elton Beds and comprises olive-green and grey flaggy mudstones and siltstones with occasional thin limestone beds, especially in the upper part. Shergold and Shirley (1968) have shown that they have a mixed shelly and graptolitic fauna in the southern part of the outcrop around Stanway and a mainly shelly fauna to the north-east. The topmost 100 ft (30 m) are equivalent to the lower part of the Lower Bringewood Beds and are transitional to the Aymestry Group. They consist of flaggy calcareous siltstones with fine-grained limestone nodules, the nodules becoming more abundant upwards and coalescing into nodular limestone beds as the base of the Aymestry Group is approached.

Within the Wenlock Edge area the best sections in the Lower Ludlow Shales are around Upper and Lower Stanway. About 18 ft (5.5 m) of grey flaggy siltstone with many beds of nodular limestone, near the base of the formation, are seen in a track [SO 5326 9148] about 750 yd (685 m) E.N.E. of Stanway Manor. A further 60 ft (8 m) of olive-green flaggy siltstones with occasional thin calcareous beds crop out intermittently in the stream [SO 5312 9122]–[SO 5332 9140] east of Stanway Manor. These beds contain a fauna typical of the lower part of the Shales which includes the brachiopods Aegiria [Chonetoidea] grayi, Leptaena rhomboidalis, Skenidioides lewisii and the trilobite Dalmanites sp. An old quarry [SO 5346 9088] near the top of the shales, 900 yd (820 m) E.S.E. of Stanway Manor, shows 24 ft (7.3 m) of flaggy siltstones with many beds of grey limestone nodules and beds of tabular grey limestone. The limestone beds contain abundant small brachiopods with crinoids and other shell debris.

North of Wrensnest [SO 553 928] the outcrop of the Lower Ludlow Shales is largely obscured by boulder clay and sections are infrequent. Disturbed beds are seen in the stream [SO 5675 9474] south of Easthope, adjacent to the N.–S. fault which passes through that village. The highest beds of the Shales, included by Robertson (1927, p. 93) in the Aymestry Group, are seen below the weir [SO 5736 9426] at Cottage Pool. Twelve feet (3.7 m) of calcareous siltstone with occasional thin platy limestone and nodular limestone beds are seen which have yielded a very large fauna typical of the Lower Bringewood Beds including the bryozoan Ptilodictya lanceolata (Goldfuss), the brachiopods Leptostrophia filosa (J. de C. Sowerby), Shagamella ludloviensis Boucot and Harper ['Chonetes' lepisma (of authors)] and Strophonella euglypha (Hisinger), the bivalve Cypricardinia subplanulata Reed, the trilobite Dalmanites myops (Konig), the ostracod Hemsiella [Beyrichia]maccoyiana and the graptolite Monograptus cf. chimaera (Barrande). There are no significant exposures north of Easthope apart from a section in a small fault-trough in Lilleshall Quarry [SO 5742 9672] which shows buff calcareous silty mudstone with occasional nodular limestone beds overlying the Wenlock Limestone.

Aymestry Group

The crop of the Aymestry Group extends northwards from Topley [SO 527 900] to the vicinity of Henmoor Hill [SO 595 972]. It occupies the upper part of the broad dip slope which forms the north-west side of Corve Dale. Unlike the continuous dip slope formed by the Wenlock Limestone, this slope is broken by a number of joint-controlled valleys and 'deans' (Hoare in Greig and others 1968, p. 162). The Aymestry Group has a general south-easterly dip of about to degrees. However, in the valley between Moggforest [SO 561 939] and Larden Hall, the dip swings to easterly at 15 to 20 degrees, probably in association with a N.–S. fault through Larden Hall which causes a dextral displacement of the crop by about 250 yd (230 m).

The Group is about 200 ft (60 m) thick to the south of Cottage Pool [SO 573 943] but thins northwards to about 100 ft (30 m) on Henmoor Hill. It comprises grey nodular limestones with siltstone beds and partings, and within the Group there are several ill-defined calcareous subgroups of beds separated by less calcareous beds. The calcareous subgroups, which comprise nodular limestones with thin siltstone partings, as opposed to the alternations of limestone and siltstone of the less calcareous beds, may be lenticular in form. As the Aymestry Group is traced to the north-east it becomes less calcareous in aspect, and at the eastern limit of the area it consists chiefly of alternations of argillaceous nodular limestone and calcareous siltstone. The decrease in calcareous content is accompanied by a decrease in the height of the ridge formed by the Group.

The Aymestry Group is well exposed in the southern part of the outcrop. The basal beds, silty calcareous mudstones with beds of limestone nodules and of shelly limestone, are seen [SO 5275 9013] immediately north of Topley, and slightly higher strata comprising bedded argillaceous nodular limestone with some calcareous siltstone beds are well exposed in an old quarry [SO 5333 9006] south-east of Whitbach and also in another quarry [SO 5462 9122] south-east of Lower Stanway. Twenty feet (6 m) of bedded argillaceous nodular limestone and calcareous siltstone, within the main part of the Group, are seen in an old quarry [SO 5546 9260] south-east of Wrensnest. An old quarry [SO 5462 9055] 180 yd (165 m) W.N.W. of Hopescross shows 10 ft (3 m) of bedded silty limestone and limestone with some siltstone beds overlain by 20 ft (6 m) of bedded calcareous flags with limestone beds and nodules. The faunas suggest that the upper beds are transitional to the Upper Ludlow Shales.

There are good sections in the Aymestry Group in the valleys which run south-eastwards from Moggforest [SO 561 939] and Larden Cottage [SO 570 944]. Calcareous siltstones and nodular limestones near the base of the Group are exposed [SO 5633 9380] east-south-east of Moggforest. About 300 yd (275 m) to the south-south-east an old quarry [SO 5644 9353] shows about 20 ft (6 m) of bedded calcareous siltstone and nodular siltstone with shelly and nodular limestone beds. The large fauna includes the brachiopods 'Camarotoechia'nucula, Dayia navicula (J. de C. Sowerby), Howellella elegans, Isorthis orbicularis (J. de C. Sowerby), Salopina lunata (J. de C. Sowerby) and Sphaerirhynchia wilsoni (J. Sowerby) and the bivalve Fuchsella amygdalina (J. de C. Sowerby), and resembles that from the Dayia Shales of Elles and Slater (1906, p. 198) of the Ludlow area. Beds with a similar fauna are seen [SO 5651 9342] 150 yd (137 m) farther down the valley and in an old quarry [SO 5730 9421] in the valley south-east of Larden. Cottage. Farther down this valley, in the stream [SO 5757 9400], buff calcareous silty flags with nodular limestone beds are exposed. These beds, near the top of the Group, contain abundant Shaleria ornatella (Davidson) and other brachiopods.

North of Brockton much of the outcrop is drift covered and there are few exposures.

Upper Ludlow Shales

The crop of the Upper Ludlow Shales extends north-eastwards from the southern margin of the area at Broadstone Mill [SO 547 900] through Shipton and Brockton to Bourton. A strike fault increases the width of the crop between Shipton and Larden Hall. The Shales occupy the lower part of the dip slope of the Aymestry Group ridge and consequently their thickness is difficult to estimate with accuracy. They appear to be about 200 ft (60 m) thick in the south, thinning to 100 ft (30 m) at Bourton, although Robertson (1927, p. 26) estimated that they maintained a thickness of about 100 ft (30 m) from Much Wenlock to the Craven Arms area. They have a general south-easterly dip of about to degrees.

The Upper Ludlow Shales maintain a fairly constant lithology along the crop. They comprise olive-green and buff flaggy siltstones, commonly calcareous with occasional thin platy and nodular limestone and silty limestone beds. The limestone beds are more common towards the base of the formation. Towards the top of the Shales the siltstones become coarser and locally there are thin beds of fine-grained sandstone.

About 18 ft (5.5 m) of calcareous siltstones with occasional limestone beds, near the base of the Shales, are exposed in the old quarry [SO 5476 9067] behind Rock Houses, north of Hopes-cross. Farther north there are several sections in the vicinity of Shipton. The basal beds, transitional to the Aymestry Group, crop out in the stream [SO 5584 9205] west of the village and higher beds, buff flags and calcareous flags with occasional limestone beds, are exposed to 30 ft (9 m) in an old quarry [SO 5626 9199] north-north-east of the church. This latter locality contains a fauna including the annelid Serpuloides [Serpulites] longissimus (J. de C. Sowerby), the brachiopods 'Camarotoechia' nucula, Protochonetes ludloviensis Muir-Wood and Salopina lunata, the bivalve Fuchsella amygdalina and the cephalopod Michelinoceras bullatum (J. de C. Sowerby). The topmost beds of the Shales together with the overlying Ludlow Bone Bed and basal Downton Castle Sandstone (p. 43) are seen in the lane [SO 5629 9176] south-east of the church. The Upper Ludlow Shales here comprise grey and buff calcareous siltstone with thin fossiliferous limestone beds and a large and typical fauna including the annelid Serpuloides [Serpulites] longissimus, the brachiopods 'Camarotoechia'nucula, Craniops implicata, Lingula minima J. de C. Sowerby, Orbiculoidea rugata (J. de C. Sowerby), Protochonetes ludloviensis and Salopina lunata, the bivalves Actinopterella tenuistriata (McCoy), Fuchsella amygdalina and Pteritonella retroflexa (Wahlenberg) and the trilobite Acastella spinosa (Salter).

There are also sections through the greater part of the Shales around Brockton. The basal beds are seen in the stream [SO 5761 9398] north-west of the village and higher beds, flaggy calcareous siltstones, in the old quarry [SO 5774 9394] behind the school. The topmost beds, again overlain by the Ludlow Bone Bed and basal Downton Castle Sandstone are exposed in the road cutting [SO 5788 9386] 80 yd (73 m) N.E. of the cross-roads. A similar section [SO 5857 9475] south-east of Patton House Farm shows 15 to 20 ft (4.5–6 m) of flaggy calcareous siltstone overlain by 5 ft (1.5 m) of olive shaly mudstone. The Ludlow Bone Bed, only 0.25 in (6.4 mm) thick, occurs 1 ft (0.3 m) from the base of the mudstone, so that the topmost 4 ft (1.2 m) are included within the Downton Castle Sandstone (Robertson 1927, p. 93). Flaggy calcareous siltstone and limestone are seen at the roadside [SO 5954 9634] immediately east of the cross-roads at Bourton.

Chapter 6 Old Red Sandstone

Old Red Sandstone rocks occur in the south-eastern corner of the area. They have a gentle south-easterly dip and have a conformable relationship with the underlying Upper Ludlow Shales. The stratigraphical sequence within the Old Red Sandstone is shown on the side margin of the map; only the lower part of the Lower Old Red Sandstone (the Downton Series and the lower part of the Ditton Series) is present, though higher beds occur to the south of the area on Brown Clee Hill. The soft siltstones ('marls') of the Downton Series floor the low ground of Corve Dale while the 'Psammosteus' Limestones and sandstones near the base of the Ditton. Series give rise to the strong feature south-east of Great Oxenbold [SO 594 920] and Coates Farm [SO 586 908].

During late Silurian and early Old Red Sandstone times, major changes occurred in the palaeogeography of Wales and Central England. The main phase of the Caledonian mountain building movements began and their final effect in Middle Old Red Sandstone times was to raise the sediments of the Welsh Geosyncline into a folded mountain chain. The shallow shelf-sea which covered much of the Midlands and Welsh Borders in Silurian times, as well as much of the 'basinal' area to the north-west, was converted into a subsiding delta-plain fed with sediment from the rising mountains, and there was a gradual transition from a marine to a continental environment. The lowest member of the Old Red Sandstone, the Ludlow Bone Bed, was formed during a pause in sedimentation by the winnowing and concentration of fish remains and other debris on the floor of a shallow sea. The lower part of the overlying Downton Castle Sandstone resembles the Upper Ludlow Shales in lithology but has a fauna of horny brachiopods and fish in place of the marine shelly fauna of the older rocks. These sediments, probably laid down off shore under brackish-water conditions, are followed by the deltaic sandstones of the higher part of the formation. The Temeside Shales show a temporary return to the depositional conditions of the lower part of the Downton Castle Sandstone. The sediments of the Ledbury Group were laid down in a deltaic environment at or near sea level. Local marine incursions are marked by the occurrence of bands of molluscs, but it is uncertain whether the main mass of the sediments was laid down in the tidal zone or on the sub-aerial part of the delta (Allen and Tarlo 1963; Ball and others 1961). The overlying Ditton Series rocks have a predominantly fluviatile origin. Chemical limestones and occasional mollusc bands in the lower part (the 'Psammosteus'Limestones) indicate respectively the occurrence of temporary lakes and of brief marine incursions.

Downton Series

Ludlow Bone Bed and Downton Castle Sandstone

The Ludlow Bone Bed is a brown sandstone or sandy mudstorte with abundant fish remains, some fragments of other fossils and small phosphatic concretions. In the Wenlock Edge area it may occur as several closely spaced lenticular beds, though farther south it is usually a single bed up to 2 in (50 mm) thick. At Shipton it occurs as two impersistent beds 2 in (13 mm) thick and 4 in (100 mm) apart in the lane [SO 5631 9175] 160 yd (146 m) E.38°S. of the church.

The Downton Castle Sandstone is 20 to 30 ft (6–9 m) thick, comprising 3 to 6 ft (1–2 m) of olive-green shales or mudstones at the base overlain by fine-grained, micaceous, yellowish buff sandstone, locally flaggy and false bedded, but commonly massive. It is poorly exposed though its outcrop can usually be traced from fragments in the soil. At Shipton [SO 5631 9175] the basal 8 ft (2.4 m) of the Sandstone are seen overlying the Ludlow Bone Bed. Buff silty shales, 3 ft (0.9 m) thick, are succeeded by yellow flaggy sandstones. North of Shipton there is a small area [SO 562 921]–[SO 567 928] of the Sandstone on the north-west side of a strike fault, and at Brockton the basal beds are seen in the stream [SO 5792 9372] (Robertson 1927, pp. 93–4)

Temeside Shales

The Temeside Shales consist of green, purple and grey blocky mudstones with beds of yellowish green, micaceous flaggy sandstone. They have a fauna similar to, but more abundant than, that of the Downton Castle Sandstone. The Shales probably vary in thickness from about 40 to 80 ft (12–24 m), but owing to paucity of exposures these thicknesses are only tentative. Grey silty micaceous shales with thin calcareous sandstone beds are seen in the stream [SO 5795 9373] about 80 yd (73 m) W. of the Castle Mound, Brockton. They contain Lingula sp., small bivalves and occasional fish fragments.

Ledbury Group

The Ledbury Group occupies the low ground of Corve Dale and the lower part of the steep slope to the south-east of the Dale. It is about 1500 ft (460 m) thick and consists of red and purple siltstones ('marls'), commonly unstratified, with beds of purple and dark greenish purple, coarsely micaceous sandstone. The sandstones are locally false-bedded and sometimes contain marl pellets. Bright red marls with green reduction spots ('fish eyes') occur particularly at the top of the Group and beds of small calcareous nodules ('race') are also present locally.

South-east of Shipton the topography and occurrence of sandstone debris indicate that sandstones occur fairly regularly from the base of the Ledbury Group to within 300 to 400 ft (90–120 m) of the top. Many of these sandstone features, especially the higher ones, continue north-eastwards towards Weston, displaced at intervals by minor faults. East of the River Corve at Shipton three small faults with westerly down-throw follow approximately N.–S. courses. The remaining faults cross the strike of the beds more or less at right angles. The beds are rarely exposed but 5 ft (1.5 m) of reddish brown and grey, fine-grained micaceous sandstone are seen in the left bank of the Corve [SO 5869 9329] 785 yd (718 m) N.14°W. of Skimblescott. Thin sandstones are also present north of the Corve between Moorhouse Covert [SO 577 927] and Bradeley [SO 596 949].

Ditton Series

Rocks of the Ditton Series occupy the south-eastern corner of the area where the basal 800 ft (240 m), approximately, of the Series are present. The base of the Series is taken at the base of the 'Psammosteus'Limestone (Ball and others 1961, p. x 80), a group of concretionary limestones, of varying number, which crops out on the Corve Dale escarpment and includes, and is overlain by, a succession of rocks in which the proportion of sandstones and cornstone-conglomerates is significantly higher than in the Downton Series below. The principal faunal change in the lower Old Red Sandstone takes place at about this level where the Traquairaspis fauna of the Downton Series is replaced by the Pteraspis fauna of the beds above (White 1950, p. 56), although there is overlap between the two faunas. In the Wenlock Edge area a quartz-bearing cornstone-conglomerate marks the base (Greig and others 1968, p. 210).

The Ditton Series comprises red and purple siltstones ('marls') with abundant flaggy, fine-grained sandstones and less frequent cornstone-conglomerates. The latter are made up of pebbles of calcareous siltstone, sandstone and concretionary limestone in a calcareous sandy matrix and occur in lenticular beds which may be 20 ft (6 m) thick. These conglomerates yield most of the fish fragments in the Ditton Series. Chemical concretionary limestones or cornstones (as, for example, the 'Psammosteus' Limestones) also occur within the Series and the following upward sequence of lithologies is commonly observed: cornstone-conglomerate; sandstone, becoming flaggy and shaly upwards; marl, with cornstone nodules near the top; cornstone; cornstoneconglomerate. The primary control on sedimentation was probably tectonic, but the effect of climate can be seen in the change from cornstone, a product of prolonged desiccation, to cornstone-conglomerate, deposited by fast-flowing water.

The basal conglomerate, with limestone and quartz pebbles, is 2 ft 6 in (0.76 m) thick in the stream [SO 5960 9144] about 630 yd (576 m) S.S.E. of Great Oxenbold. Two beds of nodular limestone, 4 ft (1.2 m) thick, occur in the overlying 30 ft (9 m) of marls, sandstones and cornstone-conglomerates, and debris higher in the stream probably indicates a third unexposed bed. Traces of higher beds, mainly sandstones, occur for about 400 yd (370 m) upstream. Both limestones appear to have been worked in Oxenbold Coppice to the north. There are many exposures of higher beds in the Ditton Series, sandstones, marls and cornstone-conglomerates, in the streams in the extreme south-east corner of the area.

Chapter 7 Carboniferous

Carboniferous rocks occupy the extreme north-western corner of the area, around Bentleyford [SO 506 998]. They are part of the Coed-yr-Allt Beds of the Upper Coal Measures and consist of mudstones, siltstones and sandstones with thin coal seams and associated seatearths, and a bed of Spirorbis limestone. To the south-east they are faulted against Uriconian rocks by the Church Stretton Fault (F1) except in the stream [SO 5084 9933] about 600 yd (550 m) S.S.E. of Bentleyford where rocks of doubtful Silurian age (p. 26) are present immediately north-west of the fault.

The Coed-yr-Allt Beds outcrop is almost entirely obscured by boulder clay and the only exposures are in the stream south-south-east of Bentleyford. A thin coal seam, broken and veined with calcite, is seen [SO 5087 9940] just downstream from the supposed Silurian rocks, and grey sandstones and mudstones interbedded with mottled mudstones occur farther downstream. About 230 yd (210 m) S.E. of Bentleyford a small fault crosses the stream and on its west side grey sandstones and shales with a 4 ft 6 in (1.37 m) bed of compact grey limestone of 'Spirorbis' type are exposed. A further coal seam is seen [SO 5070 9974] about 100 yd (90 m) from the farm.

Chapter 8 Structure

The broad structural pattern in the Wenlock Edge area follows north-easterly, Caledonoid, alignment. The main structural feature is the Church Stretton Fault Complex or Eastern Uriconian. Axis (Pocock and others 1938, p. 169) which cuts across the north-western corner of the map from Lawley to Frodesley Lodge [SO 518 998] and with which are associated the thrusts bounding the Cambrian outcrop at Hill End [SO 506 944]. To the north-west of the Fault Complex is a small area of Carboniferous rocks forming part of the Leebotwood Basin (Pocock and others 1938, p. 175). The remaining, greater, part of the area, south-east of the Fault Complex, is structurally simple, comprising south-easterly dipping rocks of Ordovician, Silurian and Old Red Sandstone age on the north-west limb of the Brown Clee Syncline (Ball and others 1961, p. 209).

The Leebotwood Basin

In the Leebotwood Basin Upper Coal Measures and Bunter Series rocks are downfaulted on the north-western side of the Church Stretton Fault Complex. This indicates that movements occurred on the Eastern Uriconian Axis until at least Triassic times. Within the area of the map, a small part of the Basin is represented by the outcrop of Coed-yr-Allt Beds around Bentleyford [SO 506 998]. The south-eastern limit of the Basin is formed by the Church Stretton Fault (F1).

The Eastern Uriconian Axis

This includes the Uriconian rocks of Stoneacton and Hill End and the Church Stretton Fault Complex which affects rocks varying in age from Uriconian to Upper Carboniferous. The development of the structures within the Complex has probably been controlled by movements along three major faults, F1 (Church Stretton Fault), F2 (Lawley Fault) and F3 (Cwms–Hoar Edge Fault), described by Cobbold (1927, p. 565) in the Comley district [SO 485 964] to the west of the present area. Movements along these faults appear to have taken place from Longmyndian times onwards.

The Church Stretton Fault (F1) has a straight course across the north-western corner of the area and forms the north-western limit of the Eastern Uriconian Axis. On the north-west side of Lawley [SO 501 988] it appears to consist of two parallel closely spaced fractures. In this area it behaves as a normal fault with a westerly downthrow.

The Lawley Fault (F2) follows a sinuous course along the south-eastern side of that hill. It appears to merge with F1 at the northern limit of the area [5160 9999]. The sinuous course of the fault, which is also apparent farther to the southwest around Comley and Caer Caradoc (Sheet SO49), led Cobbold (1927, p. 565) to postulate that the fault had a westward hade of roughly 45 degrees and that Uriconian and Lower Cambrian rocks had been pushed over younger rocks to the south-east. There is subsidiary faulting within the Cambrian north-west of Coppice House. The west-northwesterly trending fault just south of Frodesley Lodge is the southern end of the Coundmoor Fault (Pocock and others 1938, p. 173).

The Cwms–Hoar Edge Fault (F3) appears to die out just within the Wenlock Edge area [SO 501 976]. Mitchell (in Greig and others 1968, pp. 269–70) has shown that farther to the southwest near Cwms Plantation [SO 480 945] this fault is closely connected with the Sharpstones and Hill End thrusts. It appears that the Uriconian rocks of Cardington. Hill and Stoneacton [SO 507 937] have moved northwards over Caradoc Series strata along the line of the Sharpstones Thrust and its branch, the Hill End Thrust, and that the accompanying tear fault to the west is the Cwms–Hoar Edge Fault. An E.–W. fault with a southerly downthrow north of Gretton [SO 515 953] may also be associated with these movements. This fault and the two thrusts are clearly pre-Silurian in age as they pass beneath the unconformable basal Silurian.

The Ordovician rocks in the area between Hoar Edge [SO 504 974] and Church Preen [SO 544 982] have a general south-easterly dip. On Hoar Edge, close to the Church Stretton Fault Complex, the dip is from 50 to 70 degrees, but there is a gradual decrease in a south-easterly direction to 10 to 20 degrees adjacent to the unconformable basal Silurian.

The Brown Clee Syncline

The greater part of the area is occupied by gently dipping Silurian and Old Red Sandstone rocks on the north-western limb of the Brown Clee Syncline. The general dip is to the south-east at about to degrees with some irregular variations in direction and amount adjacent to some faults. There are no significant folds and no major faults.

Two minor faults affect strata exposed in the Hughley Brook. A N.–S. fault to the west of the village displaces the top of the Hughley Shales dextrally by about 400 yd (365 m) but appears to die out rapidly northwards, and a second smaller fault with an easterly downthrow displaces the crop [SO 576 990] of the Hughley Shales west-south-west of Newfoundland. Between these two faults the dip of the beds is much more variable than usual.

A number of faults affect the Wenlock Limestone and Tickwood Beds between Stars Coppice [SO 507 905] and Pilgrim Cottage [SO 550 938], but it has not been possible to trace them for any distance within the underlying Wenlock Shales or the overlying Lower Ludlow Shales. A N.–S. fault through Stars Coppice has a westerly downthrow of about 180 ft (55 m). It displaces the crop of the Wenlock Limestone by about 500 yd (457 m) and gives rise to a marked kink in the scarp. Two minor dip faults cut the scarp at Black Wood [SO 517 908] and near Upper Stanway [SO 527 917], and a strike fault with a small north-westerly downthrow broadens the outcrop of the Wenlock Limestone at Wilderhope [SO 544 928]. A dip fault west-north-west of Pilgrim Cottage causes a distinct bend in the scarp, although the north-easterly downthrow is less than 30 ft (9 m).

The most important fault system within the Silurian and Old Red Sandstone extends from the southern margin of the area [SO 555 900] near Holdgate Moor through Shipton and Easthope, and thence to Henmoor Hill [SO 597 973]. South-west of Bowgate [SO 560 907] it comprises a single fault which runs beneath the alluvium of the Trow Brook. At Bowgate this fault splits into a N.–S. fault with an easterly downthrow which displaces the Temeside Group and dies out in the Upper Ludlow Shales and a north-north-easterly trending fault with a westerly downthrow of about 40 ft (12 m) which also displaces the Temeside Group and passes through Shipton. towards Larden Hall. Near the Hall it is joined by a strike fault with a northwesterly downthrow of nearly 200 ft (60 m) which causes a repetition of the Downton Castle Sandstone north of the village. North of Larden Hall the combined fault dextrally displaces the Aymestry Group outcrop by about 350 yd (320 m). At Easthope this fault has a westerly downthrow of approximately 150 ft (137 m), but the throw decreases northwards and the fault terminates against an east-northeasterly trending fault at Hilltop [SO 5699 9634]. In the angle between these two faults there is an upfaulted area of Wenlock Limestone Reef Facies and Wenlock Limestone. The second fault extends from the bottom of the scarp near Easthopewood to the eastern limit of the area near Henmoor Hill where it displaces the base of the Aymestry Group sinistrally by about 100 yd (91 m). Minor branch fractures to the north form the trough fault in Lilleshall Quarry (p. 34).

Three minor N.–S. faults with westerly downthrows displace sandstones in the Ledbury Group to the east of Shipton and three dip faults affect the beds to the east towards Weston [SO 598 929].

Chapter 9 glacial, post-Glacial and recent deposits

The succession and distribution of superficial deposits is shown on the geological map. These deposits, mainly boulder clay, cover a large proportion of the ground to the north-west of Wenlock Edge and smaller areas farther to the south-east. Glacial sand and gravel occur only locally and in very small amounts. The depositional sequence in the area indicates only one period of glaciation, correlated with the maximum development of an ice-sheet from the Irish Sea which spread southwards across the Shropshire Plain and down the major valleys of the area (Figure 3).

Morainic drift

To the south of Gretton [SO 515 953] there is a well-marked topographic feature which faces east and forms the eastern boundary of a morainic deposit extending westwards through Cardington village. This deposit has an irregular boundary and consists of a roughly-bedded coarse clayey gravel which has been exposed in a number of shallow excavations and has a maximum known thickness of 26 ft (8 m). It may be a terminal moraine which was deposited in front of the ice north of Cardington. Hill.

Boulder clay

The low ground to the north-west of Lawley, between Lawley and Hoar Edge, and in the Ruckley and Langley valley, is all covered with boulder clay derived from the Irish Sea ice-sheet. In the latter valley there is an abundance of 'kettleholes'. Usually between 15 and 30 yd (14–27 m) across they are associated with sandy areas within the boulder clay sheet.

A strong drift ridge, about 700 yd (640 m) long, with steep eastern and southern banks, runs eastwards into the centre of the valley from the flank [SO 523 992] of Lodge Hill. It lies just south of the break in the Hoar Edge Grit ridge and may be a fan or delta deposited when the ice-front lay across the break.

Boulder clay covers almost all of the area between Wenlock Edge and the high ground of Hill End [SO 504 944], Yell Bank [SO 508 971] and Church Preen [SO 543 981]. To the south-west of Rushbury [SO 514 919] the boulder clay contains erratics of Welsh origin, and it appears to have been derived from ice moving up Ape Dale from the south-west (Figure 3). Boulder clay is absent from the small hill on which Rushbury stands, but it thickens steadily to the north-west. The base of the deposit rises from about 600 ft (180 m) O.D. near Rushbury to 970 ft (295 m) O.D. on Yell Bank, north of Cardington. It is a yellowish brown stony clay with erratics including grey sandstone and coarse grey grit, rhyolite and tuff of Uriconian type and sporadic red sandstone pebbles possibly derived from the Trias. This assemblage suggests a derivation from northern ice.

There are extensive deposits of boulder clay on the Wenlock and Aymestry escarpments from Wilderhope [SO 545 928] northwards. To the west of Bourton [SO 596 963] the boulder clay reaches a height of more than 900 ft (275 m) O.D. on top of the Aymestry Group ridge. Numerous erratic boulders of northern origin have been described (Mackintosh 1879) from the vicinity of Bourton (Burton). Recent re-examination of these erratics (Wright in Greig and others 1968, p. 295) shows that they include granites similar to varieties of the Eskdale Granite of the Lake District, granophyre of possible Uriconian origin, tuffs from either the Borrowdale Volcanics or the Uriconian and subgreywacke of Longmyndian type. An area of boulder clay in Corve Dale, south of Brockton, may have been deposited by ice moving through the gap in the Aymestry Group ridge south-east of Easthope.

Sand and gravel

Glacial sand and gravel are limited to a few very small areas. A mound of gravel [SO 511 923] north-west of Rushbury may mark approximately the junction of northern and southwestern ice (Figure 3) in Ape Dale and was possibly laid down at an early stage in the retreat of the ice. Other small areas of sand and gravel lie 700 yd (640 m) N.E. of The Wood; near Plaish Hall [SO 531 966] ; south of Hughley [SO 566 974] ; at New House [SO 554 984], and north-east of Rowley [SO 596 999]. There are no sections in any of these deposits.

Head deposits

These deposits are limited to the south-eastern half of the area. They have accumulated by solifluxion processes in the bottoms of valleys and below escarpments, the material having been derived from higher ground. Most of the head accumulated under the periglacial conditions which existed after the retreat of the ice, but these deposits have been augmented by more recent hill-wash and in some of the valleys they have locally been reworked by surface water.

The most extensive deposit of head lies below Wenlock Edge, from Coats Wood [SO 530 920] northwards, and consists of buff and grey clay with limestone debris locally at least 4 ft (1.2 m) thick. Another area of clayey head occupies Hope Dale between Stanway Manor [SO 527 912] and Blackwood Farm [SO 519 901]. There is a shallow landslip in the head west of Springfield Coppice. Thin deposits of head occur in many of the valleys which cut the Aymestry Group scarp, and there is an extensive spread of grey and red clay at least 5 ft (1.5 m) thick around Moor Hall [SO 572 928] at the mouth of one of these valleys.

Alluvium

There is a marked contrast between the southerly flowing streams, the River Corve and the Eaton Brook, which have alluvial flats about 100 yd (90 m) wide, and the northerly flowing streams such as the Hughley and Bentleyford brooks which have hardly any alluvial deposits.

The flood-plain alluvium of the River Corve consists of reddish brown clay, with pebbly beds in the higher reaches north of the bridge [SO 5876 9346] on the Brockton–Weston road. There are many sections in the river banks showing about 4 ft (1.2 m) of alluvium. The Eaton Brook alluvium is also exposed to about 4 ft (1.2 m) in the banks of the stream and comprises buff and brown silty clay and clay, locally gravelly in the upper reaches of the stream.

It has been noted by Robertson (in Pocock and others 1938, pp. 212–3) that the northward flowing brooks such as the Hughley (Harley) Brook, the Bentleyford Brook [SO 509 995] and the Lawley Brook [SO 506 991] have virtually no alluvial deposits. The streams are incised below about 400 ft (120 m) O.D. and between 450 and 700 ft (137–213 m) O.D., and commonly cut down through the general boulder clay cover to the solid rock. The narrow alluvial strip along the Hughley Brook consists mainly of clayey gravel.

Peat

Small areas of peat occur at Alder Coppice [SO 563 945], and near Wood Farm, below Wenlock Edge. A section [SO 5596 9580] 100 yd (90 m) S.E. of Wood Farm showed 1 ft (0.3 m) of peat overlain by 1 ft 6 in (0.45 m) of pale clayey sand with thin-shelled molluscs in turn overlain by a further 1 ft (0.3 m) of peat. Peat occupies a small hollow [SO 583 972] east of Presthope Farm, and 2 ft (0.6 m) of peat, on alluvium, occur in a small area [SO 5482 9015] north-east of Broadstone Mill.

Interpretation of glacial history

With the onset of glacial conditions, glaciers from the ice-sheet in the Shropshire Plain extended southwards along the Church Stretton Valley (Sheet SO49) and the northern part of Ape Dale. Possibly at the same time Welsh ice from the Camlad Valley advanced around the southern end of the Long Mynd and moved eastwards into the southern part of Ape Dale. The suggested limits of the glaciers in the Wenlock Edge and adjacent areas are shown on (Figure 3). It is not certain if the maxima of the Welsh ice and the Shropshire Plain ice occurred at the same time. At the peak of the glaciation the major valleys were probably occupied by ice although the intervening ridges were apparently not overwhelmed except in one or two places. In the Easthope area northern ice surmounted the Wenlock and Aymestry ridges and penetrated down the Easthope–Brockton valley at least as far as the Corve. As the ice-sheet waned, it left behind extensive sheets of boulder clay which, on the low ground at least, have been little affected by later erosion.

Selected references

ALLEN, J. R. L. and TARLO, L. B. 1963. The Downtonian and Dittonian Facies of the Welsh Borderland. Geol. Mag., 100, 129–55.

BALL, H. W., DINELEY, D. L. and WHITE, E. I. 1961. The Old Red Sandstone of Brown Clee Hill and the adjacent area. Bull. Brit. Mus. (Nat. Hist.) Geol., 5, 175–310.

BANCROFT, B. B. 1933. Correlation-tables of the stages Costonian–Onnian in England and Wales. (Privately printed). Blakeney, Gloucestershire.

COBBOLD, E. S. 1927. The Stratigraphy and Geological Structure of the Cambrian Area of Comley (Shropshire). Quart. J. Geol. Soc. Lond., 83, 551–73.

COCKS, L. R. M. and RICKARDS, R. B. 1969. Five boreholes in Shropshire and the relationships of shelly and graptolitic facies in the Lower Silurian. Quart. J. Geol. Soc. Lond., 124 (for 1968), 213–38.

CROSFIELD, M. C. and JOHNSTON, M. S. 1914.  A study of ballstone and the associated beds in the Wenlock Limestone of Shropshire. Proc. Geol. Assoc., 25, 193–224.

DEAN, W. T. 1958. The faunal succession in the Caradoc Series of south Shropshire. Bull. Brit. Mus. (Nat. Hist.) Geol., 3, 193–231.

DEAN, W. T. 1960. The Ordovician Rocks of the Chatwall District, Shropshire. Geol. Mag., 97, 163–71.

DEAN, W. T. 1964. The geology of the Ordovician and adjacent strata in the southern Caradoc district of Shropshire. Bull. Brit. Mus. (Nat. Hist.) Geol., 9, 257–96.

DINELEY, D. L. 1960. Shropshire Geology: An outline of the tectonic history. Field Studies, 1, 86–108.

ELLES, G. L. and SLATER, I. L. 1906. The Highest Silurian Rocks of the Ludlow District. Quart. J. Geol. Soc. Lond., 62, 195–222.

GREIG, D. C., WRIGHT, J. E., HAINS, B. A. and MITCHELL, G. H. 1968. Geology of the country around Church Stretton, Craven Arms, Wenlock Edge and Brown Clee. Mem. Geol. Surv.

HAINS, B. A. 1969. The Geology of the Craven Arms area (Explanation of 1: 25 000 Geological Sheet SO48). Geol. Surv. Gt. Brit.

HOLLAND, C. H. and LAWSON, J. D. 1963. Facies patterns in the Ludlovian of Wales and the Welsh Borderland. Lpool. Manchr. Geol. J., 3, 269–88.

HOLLAND, C. H. and WALMSLEY, V. G. 1959. A Revised Classification of the Ludlovian Succession at Ludlow. Nature, Lond., 184, 1037–9.

HOLLAND, C. H. 1963. The Silurian Rocks of the Ludlow District, Shropshire. Bull. Brit. Mus. (Nat. Hist.) Geol., 8, 93–171.

MACKINTOSH, D. 1879. Results of a Systematic Survey, in 1878, of the Directions and Limits of Dispersion, Mode of Occurrence, and Relation to Drift-deposits of the Erratic Blocks or Boulders of the West of England and East of Wales, including a Revision of Many Years' previous Observations. Quart. J. Geol. Soc. Lond., 35, 425–55.

POCOCK, R. W., WHITEHEAD, T. H., WEDD, C. B. and ROBERTSON, T. 1938. Shrewsbury District including the Hanwood Coalfield. Mem. Geol. Surv.

ROBERTSON, T. 1927. The Highest Silurian Rocks of the Wenlock District. Summ. Prog. Geol. Surv. for 1926, 80–97.

SALTER, J. W. and AVELINE, W. T. 1854. On the "Caradoc Sandstone" of Shropshire. Quart. J. Geol. Soc. Lond., 10, 62–75.

SHERGOLD, J. H. and SHIRLEY, J. 1968. The faunal-stratigraphy of the Ludlovian rocks between Craven Arms and Bourton, near Much Wenlock, Shropshire. Geol. J., 6, 119–38.

STUBBLEFIELD, C. J. 1930. A New Upper Cambrian Section in South Shropshire. Summ. Prog. Geol. Surv. for 1929, Pt 2, 54–62.

WHITE, E. I. I950. The vertebrate faunas of the Lower Old Red Sandstone of the Welsh Borders. Bull. Brit. Mus. (Nat. Hist.) Geol., 1, 51–67.

WHITTARD, W. F. 1925. Notes on Valentian Rocks in Shropshire. Proc. Geol. Assoc., 36, 378–81.

WHITTARD, W. F. 1928. The Stratigraphy of the Valentian Rocks of Shropshire. The Main Outcrop. Quart. J. Geol. Soc. Lond., 83, (for 1927), 737–59.

WHITTARD, W. F. 1932. The Stratigraphy of the Valentian Rocks of Shropshire. The Longmynd–Shelve and Breidden Outcrops. Quart. J. Geol. Soc. Lond., 88, 859–902.

WHITTARD, W. F. 1952. A Geology of South Shropshire. Proc. Geol. Assoc., 63, 143–97. 1955–67. The Ordovician Trilobites of the Shelve Inlier, West Shropshire. Parts I–IX. (Includes Relationships of the Shelve Trilobite Faunas by W. T. Dean). Palaeont. Soc. [Monogr.]

WRIGHT, J. E. 1968. The Geology of the Church Stretton area (Explanation of 1: 25 000 Geological Sheet SO49). Geol. Surv. Gt. Brit.

ZIEGLER, A. M., COCKS, L. R. M. and MCKERROW, W. S. 1968. The Llandovery transgression of the Welsh Borderland. Palaeontology, II, 736–82.

A more comprehensive bibliography is given in some of the above references, in particular in Greig and others (1968) and Whittard (1952).

Other publications dealing with this district

• Books
• British Regional Geology: The Welsh Borderland
• Geology of the Country around Church Stretton, Craven Arms, Wenlock Edge and Brown Clee, (Explanation of One-inch Geological Sheet 166, New Series)
• The geology of the Church Stretton area (Explanation of 1:25 000 Geological Sheet SO 49)
• The geology of the Craven Arms area (Explanation of 1:25 000 Geological Sheet SO 48)
• Geological maps
• 'Ten-mile' map of Great Britain, Sheet 2 (1: 625 000)
• Overprinted with sheet lines of one-inch Geological Series
• One-inch to one mile (1:63 360)
• Church Stretton (166) Sheet, Solid
• Church Stretton (166) Sheet, Drift
• 1: 25 000
• Church Stretton (SO49)
• Craven Arms (SO48)
• Wenlock Edge (SO59)
• Tectonic maps
• Tectonic map of Great Britain and Northern Ireland (1:1 584 000)
• Aeromagnetic maps
• 'Ten-mile' map of Great Britain, Sheet 2 (1:6250 000)
• Diagram Edition, Sheet 5 (1:250 000) English Midlands and Welsh Borders

Figures

(Figure 1) Correlation of the Caradoc Series of southern Shropshire.

(Figure 2) Lateral variation in the Wenlock Limestone, Reef Facies and Tickwood Beds.

(Figure 3) Suggested limits of glaciers in the Church Stretton district.

(Figure 4) [Unumbered in original] Ludlow Series – classification.