The BGS Lexicon of Named Rock Units — Result Details
Garsdale Limestone Formation
| Computer Code: | GAL | Preferred Map Code: | GaL |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Holkerian Substage (CQ) — Asbian Substage (CR) | ||
| Lithological Description: | The Garsdale Limestone Formation comprises dark grey biomicrosparites to porcellanous micrites (wackestone with bands of porcellaneous calcilutite) with interbedded sandstone and siltstone, numerous thin mudstone beds and rare thin coals. Three coal seams, up to 0.07 m thick, occur in the Beckermonds Scar Borehole (see below). Minor fenestral and palaeokarst surfaces occur. The formation contains the equivalent of Garwood's (1913) Bryozoa Band. Shallow marine carbonates (with some intertidal deposits). Late Holkerian to early Asbian. | ||
| Definition of Lower Boundary: | The conformable base of the formation overlies the mid to dark grey limestones of the Fawes Wood Limestone Formation. | ||
| Definition of Upper Boundary: | The top of the formation is conformable beneath the pale to mid grey limestone of the Danny Bridge Limestone Formation. | ||
| Thickness: | The formation is 41-58 m thick (Dunham and Wilson, 1985). | ||
| Geographical Limits: | Askrigg Block and Wharfedale. | ||
| Parent Unit: | Great Scar Limestone Group (GSCL) | ||
| Previous Name(s): | Horton Limestone (A) [Obsolete Name and Code: Use FWL, GAL]
(HTNL)
Horton Limestone (B) [Obsolete Name and Code: Use FWL, GAL] (HRTL) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Section | The type section is the River Clough [SD 6977 9128 to 6967 9129] in Garsdale, comprising a variety of limestones with interbedded sandstones and siltstones, and a thin coal (see Burgess, 1986, pp. 11-12). | ||
| Reference Section | Beckermonds Scar Borehole (BGS Registration Number SD88SE/1) [SD 8636 8016] from about 101 to 143 m depth, including dark grey wackestones with beds of calcilutite, three thin coal seams, and beds of mudstone concentrated near the top of the unit (see Wilson and Cornwell, 1982). | ||
| Reference Section | BGS Raydale Borehole (BGS Registration Number SD98SW/1) [SD 9626 8474] from about 103 to 158 m depth. Dunham and Wilson (1985, p. 28) described the formation as comprising dominantly dark grey, fine-grained wackestone with many interbeds of siltstone and mudstone, and one to four thin coal seams and seven to ten beds of calcilutite up to 1.22 m thick. | ||
| Reference(s): | |||
| Dean, M T, Browne, M A E, Waters, C N and Powell, J H. 2011. A lithostratigraphical framework for the Carboniferous successions of northern Great Britain (onshore). British Geological Survey Research Report, RR/10/007. 165pp. | |||
| Dunham, K C, and Wilson, A A. 1985. Geology of the Northern Pennine Orefield. Volume 2 Stainmore to Craven. Economic Memoir of the British Geological Survey, Sheets 40, 41 and 50, and parts of Sheets 31, 32, 51, 60 and 61(England and Wales). | |||
| Garwood, E J. 1913. The Lower Carboniferous succession in the north-west of England. Journal of the Geological Society, London, Vol.68 (for 1912), 449-586. | |||
| George, T N, Johnson, G A L, Mitchell, M, Prentice, J E, Ramsbottam, W H C, Sevastopulo, G D and Wilson, R B. 1976. A correlation of the Dinantian rocks of the British Isles. Special Report of the Geological Society of London, No 7. | |||
| Burgess, I C. 1986. Lower Carboniferous sections in the Sedbergh district, Cumbria. Transactions of the Leeds Geological Association, Vol. 11, 1-23. | |||
| Wilson, A A and Cornwell, J D. 1982. The Institute of Geological Sciences borehole at Beckermonds Scar, North Yorkshire. Proceedings of the Yorkshire Geological Society, Vol.44, 59-88. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E040 | |||