The BGS Lexicon of Named Rock Units — Result Details

Three Yard Limestone Member

Computer Code: TYL Preferred Map Code: TYL
Status Code: Full
Age range: Brigantian Substage (CX) — Brigantian Substage (CX)
Lithological Description: Limestone, packstone, fine-grained, medium and dark grey, thickly bedded, fissile and nodular in part, with styolites, thin mudstone partings, particularly in north Northumberland. Crinoid debris and foraminifera are typically characteristic, but the member if not particularly fossiliferous on the Aslton Block. A goniatite indicative of the P2c biozone has been recorded from mudstones above the Three Yard Limestone. On the Askrigg Block, the limestone is split into two leaves by a ganister-like sandstone, which thickens to up to 8m westwards; a thin coal is shown at a similar horizon in the Barnard Castle district to the east.
Definition of Lower Boundary: Taken at the generally conformable, sharp base of the first bed of limestone that overlies measures of the Alston Formation. On the Alston Block, usually overlies above a major sandstone body referred to as the Six Fathom Hazle. This typically displays a seatearth below the limestone and in north Northumberland there is typically a coal, also, a few tens of centimetres of mudstone may intervene locally.
Definition of Upper Boundary: Taken at the top of the uppermost limestone bed that is overlain by a sequence of dark grey mudstones and siltstones, in north Northumberland containing ironstone nodules locally.
Thickness: 1.8 to 4.6m on the Alston Block; 3 to 10m in the Whitehaven to Gilcrux district, north of the Lake District, an average of 2.7m on the Askrigg Block; 5 to 6m in Northumberland.
Geographical Limits: Widespread limestone member occurring throughout northern England and the Scottish Borders within the Alston Formation, stratigraphically lying below the Four Fathom Limestone and above the Five Yard Limestone on the Alston Block or the Eelwell Limestone in Northumberland.
Parent Unit: Alston Formation (AG)
Previous Name(s): Acre Limestone [Obsolete Name And Code: Use TYL] (ACRL)
Three Yard Limestone (*125)
Acre Limestone (*114)
Third Limestone (*115)
Alternative Name(s): Acre Limestone
Third Limestone
Stratotypes:
Type Section  Section in the River Greta at Scotchman's Stone, about 8km east of Bowes, Co. Durham Mills and Hull, 1976. 
Type Area  Coastal exposures at Saltpan Rocks, about 3km southeast of Berwick upon Tweed, Northumberland. 
Reference(s):
Gunn, W. 1900. The geology of the Belford, Holy Island and the Farne Islands, Northumberland. Memoir of the Geological Survey of Great Britain, Sheet 4 (England and Wales). 
John, G A L and Nudds, J R. 1996. Carboniferous biostratigraphy of the Rookhope Borehole, Co. Durham. Transactions of the Royal Society of Edinburgh: Earth Sciences, Vol.86, 181-226. 
Lumsden G I and Wilson R B. 1961. The stratigraphy of the Archerbeck Borehole, Canonbie Dumfriesshire. Bulletin of the Geological Survey of Great Britain, No.18, 1-89. 
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). 
Burgess, I C and Holliday, D W. 1979. Geology of the country around Brough-under-Stainmore. Memoir for 1:50 000 geological sheet 31 and parts of sheets 25 and 30. Geological Survey of Great Britain (England and Wales). [London: HMSO.] 131pp. 
Eastwood,T, Hollingworth, S E, Rose, W C C and Trotter, F M. 1968. Geology of the country around Cockermouth and Caldbeck. Memoir of the Geological Survey of Great Britain, England and Wales, Sheet 23. 
Mills, D A C. and Hull, J H. 1976. Geology of the country around Barnard Castle. Memoir of the Geological Survey of Great Britain. HMSO. 385pp. 
Johnson, G A L, Hodge, B L and Fairbairn, R A. 1962. The base of the Namurian and the Millstone Grit in northeast England. Proceedings of the Yorkshire Geological Society, Vol.33, 341-362. 
Young, B and Boland, M P. 1992. Geology and land-use planning: Great Broughton-Lamplugh area, Cumbria. BGS Technical Report WA/92/54. 
Day, J B W and others, 1970. Geology of the neighbourhood around Bewcastle. Memoir of the British Geological Survey, Sheet 12. (England and Wales). 
Dunham, K C. 1990. Geology of the Northern Pennine Orefield, Vol.1. Tyne to Stainmore, (2nd edition) Economic Memoir of the British Geological Survey, Sheets 19 and 25, parts of 13, 24, 26, 31, 32 (England and Wales). 
Frost, D V and Holliday, D W. 1980. Geology of the country around Bellingham. Memoir of the British Geological Survey, Sheet 13 (England & Wales). 
Chadwick, R A, Holliday, D W, Holloway, S and Hulbert, A G. 1995. The structure and evolution of the Northumberland-Solway Basin and adjacent areas. Subsurface Memoir of the British Geological Survey. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E013 E019 E011 E001 E002 E003 E004 E006 E030 E012 E050 E040 E032 E041 E051 E031 E025 E024 E020 E018 E023 E026 E014