The BGS Lexicon of Named Rock Units — Result Details

Lanark Group

Computer Code: LNK Preferred Map Code: LNK
Status Code: Full
Age range: Silurian Period (S) — Early Devonian Epoch (DL)
Lithological Description: Mainly terrestrial red-bed sequence of sandstones and conglomerates with intercalated calc-alkaline volcanic extrusive rocks.
Definition of Lower Boundary: Unconformity with the Wenlock - (probably) Ludlow inliers of the southern Midland Valley (or the equivalent disconformity in the case of the south central inliers of the Midland Valley).
Definition of Upper Boundary: Unconformity with the overlying Stratheden or Inverclyde groups (Late Devonian - Early Carboniferous age).
Thickness: Up to 2700m in Lanarkshire and 2400m in Lothian.
Geographical Limits: Southern part of the Midland Valley of Scotland (cf the Lanark basin of Bluck, 1978, and cf Smith, R A, 1995).
Parent Unit: Old Red Sandstone Supergroup (ORS)
Previous Name(s): Lower Old Red Sandstone Group (LORS)
Alternative Name(s): none recorded or not applicable
Type Area  South of the Hagshaw Hills, Lanarkshire, Scotland. See also stratotypes for component Greywacke Conglomerate, Swanshaw, Duneaton Volcanic and Auchtitench formations. 
Smith, R A, 1995. The Siluro-Devonian evolution of the southern Midland Valley of Scotland. Geological Magazine, Vol.132, 503-513. 
Bluck, B J, 1978. Sedimentation in a late orogenic basin: the Old Red Sandstone of the Midland Valley of Scotland. 249-278 in Bowes, D R and Leake, B E (eds. ) Crustal evolution in north-western Britain and adjacent regions. Special Issue of the Geological Journal No.10. 
Mitchell, G H. 1962. The geology of the neighbourhood of Edinburgh. (Explanation of Sheet 32) Third Edition. (Reprinted 1980). Memoir of the Geological Survey of Great Britain (Scotland). 
Browne, M A E, Smith, R A and Aitken, A M. 2001. A lithostratigraphical framework for the Devonian (Old Red Sandstone) rocks of Scotland south of a line from Fort William to Aberdeen. Version 3. British Geological Survey Research Report RR/01/04. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S015 S014 S023 S014 S022 S024 S024 S032 S015