The BGS Lexicon of Named Rock Units — Result Details

Fell Sandstone Formation

Computer Code: FELL Preferred Map Code: FESD
Status Code: Full, pending ratification
Age range: Chadian Substage (CI) — Holkerian Substage (CQ)
Lithological Description: Onshore areas: Medium- to thick-bedded, fine- to coarse-grained cross-bedded sandstone, locally conglomeratic, with siltstone, mudstone, seatearth and locally developed thin coals and limestones. Offshore areas: The Fell Sandstone Formation is characterized by massive, pale grey and white, fine to medium or coarse grained, poorly sorted sandstones. However, it also contains sporadic beds of grey, blocky to subfissile, non-calcareous mudstone that are up to 10 m thick, and occasional beds of dark grey, pyritic, carbonaceous mudstone. In well 43/2-1, the sandstones are partly cemented by silica. In well 44/2-1, a basal 80 m-thick sandstone unit includes partings of argillaceous dolomite, and is overlain by 12 m of thinly bedded shales and dolomites. Middle and upper massive sandstone units, 106 m and 98 m thick respectively, are separated by a 40 m-thick, relatively argillaceous interval that includes yellowish brown, reddish brown and grey mudstones.
Definition of Lower Boundary: Onshore areas: Locally unconformable, diachronous base on range of Lower Carboniferous strata, locally defined as base of Whitberry Marine Bed. Offshore areas: An erosion surface separates the Fell Sandstone and Cementstone groups at the Berwickshire coast (Smith 1967). The base of the Fell Sandstone Formation in well 43/2-1 is defined by a downward change from massive sandstones to interbedded mudstones, sandstones and limestones. It is marked by a sharp downward increase in gamma values. In well 44/2-1, the Fell Sandstone rests on thinly interbedded cementstones and clastic sediments; the boundary is taken at the top of the highest cementstone bed, and is marked by a high-velocity spike. Smith's observation (1967) that, uniquely within the lower Dinantian, the onshore Fell sandstones lack mica, argillaceous and carbonaceous detritus, may prove useful in locating the boundary in gradational offshore sections.
Definition of Upper Boundary: Onshore areas: Locally unconformable, diachronous, at base of Clattering Marine Bed, Kingsbridge Limestone or Glencartholm Volcanic Member of the Tyne Limestone Formation. Offshore areas: In the two offshore wells that have penetrated the Fell Sandstone / Scremerston formational boundary, it is defined by an abrupt facies transition from massive sandstones to argillaceous coal measures. This transition is marked by a sharp downhole decrease in gamma-ray response in well 43/2-1. A thin coal seam occurs close above the facies transition in well 44/2-1.
Thickness: Onshore areas: c.530 m maximum. Offshore areas: 382 m thick in well 43/2-1 and 338 m thick in well 44/2-1.
Geographical Limits: Onshore limits include the Tweed Basin and northern part of the Northumberland-Solway Basin from Burnmouth, Berwickshire in the northeast to Southerness, Kirkcudbrightshire in the southwest. The Fell Sandstone Formation may be continuous from the Northumberland coast across western crestal areas of the Mid North Sea High, and along its southeastern flank to the median line. The southern limit of the formation is not known, because of insufficient penetration of Dinantian strata in the central Southern North Sea area. The formation is 382 m thick in well 43/2-1 and 338 m thick in well 44/2-1. Equivalent strata are 230 m thick on the Berwickshire coast (Smith 1967).
Parent Unit: Border Group (BDR)
Previous Name(s): Craighill Sandstone Group [Obsolete Name And Code: Use FELL] (CSG)
Fell Sandstone Group (*78)
Fell Sandstone Group [Obsolete Name And Code: Use FELL] (FLS)
Border Group, Middle [Obsolete Name And Code: Use FELL] (MBG)
Middle Border Group [Obsolete Name And Code: Use FELL] (MBO)
Alternative Name(s): Middle Border Group (Part)
Stratotypes:
Type Section  Foreshore at Burnmouth Munro, 1986. 
Type Area  Sections southwest of Berwick upon Tweed. Turner et al, 1993.. 
Reference Section  North Sea well 43/2-1: 3083.5-3465.5 m (10116-11370 ft) below KB. 
Reference Section  North Sea well 44/2-1: 2862-3198 m (9390-10493 ft). 
Type Section  River White Lyne, 2km northwest of Kaysbank Farm, Bewcastle (1:50k sheet England 12, Bewcastle) Day, 1970. 
Type Section  Murton High Crags, 6.5km southwest of Berwick upon Tweed (1:50k sheets England 1 and 2, Berwick upon Tweed). Turner et al, 1993. 
Reference(s):
Cameron, T D J. 1993. Carboniferous and Devonian of the Southern North Sea. In: Knox, R W O'B & Cordey, W G (eds.) Lithostratigraphic nomenclature of the UK North Sea. (British Geological Survey, Nottingham). 
Munro, M. 1986. The sedimentology of the Fell Sandstone Group of Northumberland. Unpublished PhD thesis, University of Newcastle-upon-Tyne. 
Day, J B W and others, 1970. Geology of the neighbourhood around Bewcastle. Memoir of the British Geological Survey, Sheet 12. (England and Wales). 
Nairn, A E M. 1956. The lower Carboniferous rocks between the rivers Esk and Annan Dumfriesshire. Transactions of the Geological Society of Glasgow, 22, p.80-93. 
McMillan, A A. 2000. Upper Palaeozoic in Lintern, B C and Floyd, J D. 2000. Geology of the Kirkcudbright-Dalbeattie District. Memoir of the British Geological Survey, Sheets 5W, 5E and part of 6W (Scotland). 
Frost, D V and Holliday, D W. 1980. Geology of the country around Bellingham. Memoir of the British Geological Survey, Sheet 13 (England & Wales). 
Smith, R and McMillan, A A. 1996. Mineral investigations in the Northumberland Trough: part 3, Ecclefechan - Waterbeck area. BGS Mineral Recconnaisance Programme Open File Report No. 21. 
Turner, B R, Younger, P L and Fordham, C E. 1993. Fell Sandstone Group lithostratigraphy south-west of Berwick-upon-Tweed: implications for the regional development of the Fell Sandstone. Proceedings of the Yorkshire Geological Society. Vol.49, Part 4, 269-281. 
Smith, T E. 1967. A preliminary study of sandstone sedimentation in the Lower Carboniferous of the Tweed Basin. Scottish Journal of Geology 3, 282-305. 
Lumsden G I, Tulloch W, Howells M F and Davies A. 1967. The geology of the neighbourhood of Langholm. Memoir of the Geological Survey, Sheet 11 (Scotland). 
Craig, G Y. 1956. The Lower Carboniferous outlier of Kirkbean, Kirkcudbrightshire. Transactions of the Geological Society of Glasgow, Vol. 22, 113 - 132. 
Deegan, C E. 1973. Tectonic control of sedimentation at the margin of a Carboniferous depositional basin in Kirkcudbrightshire. Scottish Journal of Geology, Vol. 9, p. 1 - 28. 
Smith, S A and Holliday, D W. 1991. The sedimentology of the Middle and Upper Border groups (Visean) of the Stonehaugh Borehole, Northumberland. Proceedings of the Yorkshire Geological Society, Vol.48, 435-446. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S034 E005 E001 E002 E003 E004 E006 E008 E009 E012 E013 E014 S005 S006 S010 S011 E018 S006 E007