The BGS Lexicon of Named Rock Units — Result Details

Silsden Formation

Computer Code: SILS Preferred Map Code: notEntered
Status Code: Full
Age range: Arnsbergian Substage (CG) — Arnsbergian Substage (CG)
Lithological Description: Fine- to very coarse-grained pebbly feldspathic sandstone, interbedded with grey siltstone and mudstone and subordinate marine black shales, thin coals and seatearths. The lower part of the formation is dominated by thinly bedded sandstone, siltstone and mudstone forming sharp-based, normal graded beds of interpreted turbiditic origin.
Definition of Lower Boundary: A sharp base of dark grey fissile claystones of the Cravenoceras cowlingense Marine Band with diagnostic eponymous fauna, commonly underlain by a thin, fine-grained, calcareous and phosphatic sandstone of the Pendleton Formation. Elsewhere the boundary is taken at the base of the first thick quartz-feldspathic sandstone of Arnsbergian age, present above the dark grey, carbonaceous mudstone of the Bowland Shale Formation. It is taken at the base of the Mirk Fell Ironstones in the Stainmore Trough or the top of the Lower Howgate Edge Grit in the northern part of the Askrigg Block.
Definition of Upper Boundary: The base of the dark grey fissile claystones of the Isohomoceras subglobosum Marine Band, with diagnostic eponymous fauna. Where the Marine Band is not proven, the boundary is taken at the base of a thick, medium or dark grey mudstone succession, with numerous marine bands of the Samlesbury Formation.It is taken at the top of the Lower Follifoot Grit in the southern part of the Askrigg Block, or the base of a mudstone succession with Lingula in the Stainmore Trough.
Thickness: Lancaster 1000m; Bradford 400m; Askrigg Block and Stainmore Trough up to 190m.
Geographical Limits: The Craven Basin of north Lancashire and north Yorkshire, between Lancaster [SD 47 61], Pendle Hill [SD 80 41], Skipton Moor [SE 00 50] and Harrogate [SE 30 55]. Also present across the southern part of the Askrigg Block, in the Masham district [SE 29].
Parent Unit: Millstone Grit Group [See Also MIGR] (MG)
Previous Name(s): Claughton Formation (-3304)
Caton Shale (CSH)
Middleton Grit Group [Obsolete Name And Code: Part Of SILS; See Also MN] (MDGT)
Crossdale Mudstone Formation (-2117)
Silsden Moor Grit Group (-4327)
Roeburndale Formation (-4285)
Ward's Stone Sandstone Formation (-3030)
Silver Hills Sandstone Formation (-527)
Silsden Moor Grit [Obsolete Name And Code: See SILS] (SMGR)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Basal exposures at Lister Gill, overlain by interbedded turbiditic sandstone, micaceous mudstone, Marchup Grit and by dark grey fossiliferous mudstones of the Eumorphoceras yatesae and Cravenoceras edalensis marine bands along Bracken Hill Gill. Strephens et al, 1953 
Reference(s):
Waters, C N, Barclay, W J, Davies, J R and Waters, R A. In press. Stratigraphical framework for Carboniferous successions of Southern Great Britain (Onshore). British Geological Survey Research Report, RR/05/06. 
Addison, R. 1997. Geology of the Silsden and Cononley district (SE04NW and SD94NE), BGS Technical Report, WA/97/22. 
Brandon, A, Aitkenhead, N, Crofts, R G, Ellison, R A, Evans, D J and Riley, JN J, 1998. Geology of the country around Lancaster. Memoir of the British Geological Survey, Sheet 59 (England and Wales). 
Stephens, J V, Mitchell, G H and Edwards, W N. 1953. Geology of the country between Bradford and Skipton. Memoir of the Geological Survey of Great Britain, Sheet 69 (England and Wales). 
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). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E059 E060 E061 E062 E069 E070