The BGS Lexicon of Named Rock Units — Result Details

Orchard Beds

Computer Code: O Preferred Map Code: O
Status Code: Full
Age range: Arnsbergian Substage (CG) — Arnsbergian Substage (CG)
Lithological Description: A thick marine mudstone and siltstone, with the the Orchard Limestone near the base.
Definition of Lower Boundary: Generally seen as a change from fluvial sandstone and overlying seatearth or coal, if present, to marine mudstone within the Upper Limestone Formation.
Definition of Upper Boundary: Generally seen as a change to upward-coarsening arenaceous strata within the Upper Limestone Formation.
Thickness: Up to 20m in the Stirling, Airdrie, Falkirk and Glasgow districts.
Geographical Limits: Distributed throughout most of the outcrop and subcrop of the Upper Limestone Formation in the Midland Valley of Scotland.
Parent Unit: Upper Limestone Formation (ULGS)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Arden "basin". Hinxman et al., 1920. 
Reference Section  Mossneuk Borehole [BGS Reg. No. NS 88 NE/204] south of Alloa, with a base unit depth of 591m, and total thickness of 16m. 
Reference(s):
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). 
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). 
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). 
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. 
Monro, S K. 1999. Geology of the Irvine District. Memoir of the British Geological Survey, Sheet 22W and part of 21E (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). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S023 S033 S040 S041