The BGS Lexicon of Named Rock Units — Result Details

Douglas Muir Quartz-Conglomerate Member

Computer Code: DMQ Preferred Map Code: notEntered
Status Code: Full
Age range: Brigantian Substage (CX) — Brigantian Substage (CX)
Lithological Description: Consists mainly of hard, white conglomerates with subordinate pebbly sandstones with a few lenses of purplish-grey/grey mudstone up to 30cm thick. Trough cross-bedding is common in sets from 0.2m to 1.0m thick. Many of the units are upward fining in grain size. The clasts and pebbles are almost exclusively of vein quartz and well-rounded, averaging 2cm but up to 10cm in diameter, but some blocks of sandstone up to 15cm across are also present. Palaeocurrent directions indicate transport of the original sediments towards the southsouthwest.
Definition of Lower Boundary: Drawn at the base of the conglomerate of the Douglas Muir Quartz Conglomerate where it rests apparently unconformably on volcaniclastic sediments of the Kirkwood Formation, as at a natural exposure at NS 5307 7752.
Definition of Upper Boundary: The boundary is transistional, as seen at a natural exposure at NS 5730 7774, by upward passage by interbedding from conglomerate to white and pale grey sandstones of the Craigmaddie Muir Sandstones of the Lawmuir Formation.
Thickness: 20m at the type locality at Douglas Muir Quarry, and up to 70m maximum elsewhere.
Geographical Limits: Strathclyde, Scotland, and north of the River Clyde eastwards from the type area at Douglas Muir [NS 525 746] to [NS 5712 7731], site of the Strathblane-Balmore Tunnel No.8 Borehole NS57NE/28, but not in the adjacent parts of the Airdrie Sheet (31W).
Parent Unit: Lawmuir Formation (LWM)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Douglas Muir, near Milngavie, Strathclyde, Scotland. 
Reference(s):
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). 
Paterson, I B and Hall, I H S, 1986. Lithostratigraphy of the late Devonian and early Carboniferous rocks in the Midland Valley of Scotland. British Geological Survey Report, 18/3. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S030