The BGS Lexicon of Named Rock Units — Result Details

Orchard Limestone

Computer Code: OLS Preferred Map Code: notEntered
Status Code: Full
Age range: Arnsbergian Substage (CG) — Arnsbergian Substage (CG)
Lithological Description: A pale to dark grey, fine-grained, argillaceous, crinoidal, bioclastic, locally shelly limestone.
Definition of Lower Boundary: Generally seen as a change from a marine mudstone within the Upper Limestone Formation Orchard Beds.
Definition of Upper Boundary: Generally seen as a change from limestone to thick marine mudstone within the Orchard Beds of the Upper Limestone Formation.
Thickness: From 0.15m to 1.2m, or locally less, in the Airdrie, Falkirk and Glasgow districts, but reaches over 5m thickness in shelf settings in Ayrshire.
Geographical Limits: Distributed throughout most of the outcrop and subcrop of the Upper Limestone Formation in the Midland Valley of Scotland, although it can be locally difficult to recognize in Fife, for example, in on-delta settings, where thick mudstones only of the Orchard Beds are present.
Parent Unit: Upper Limestone Formation (ULGS)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Mossneuk Borehole, BGS reg. No. NS88NE/204, south of Alloa, with a unit base at 590m depth and a thickness of 0.23m. Orchard Farm is near Giffnock, Glasgow. 
Type Area  Arden "basin". Hinxman et al., 1920. 
Reference(s):
Forsyth, I H, Hall, I H S and McMillan, A A. 1996. Geology of the Aidrie district. Memoir of the British Geological Survey, Sheet 31W (Scotland). 
Hall, I H S, Browne, M A E and Forsyth, I H. 1998. Geology of the Glasgow district. Memoir of the British Geological Survey, Sheet 30E (Scotland). 
Monro, S K. 1999. Geology of the Irvine District. Memoir of the British Geological Survey, Sheet 22W and part of 21E (Scotland). 
Cameron, I B, Aitken, A M, Browne, M A E and Stephenson, D. 1998. Geology of Falkirk District. Memoir of the British Geological Survey Sheet 31E (Scotland). 
Hinxman, L W, Anderson, E M and Carruthers, R G. 1920. The economic geology of the Central Coalfield of Scotland, Area IV; Paisley, Barrhead, Renfrew. Memoir of the Geological Survey, Scotland. 
Francis, E H, Forsyth, I H, Read, W A and Armstrong, M. 1970. The geology of the Stirling district. Memoir of the Geological Survey of Great Britain, Sheet 39 (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S032 S040 S040 S030 S039 S039 S012 S023 S031 S031 S025 S024 S014 S015 S023