Douglas Muir Quartz-Conglomerate Member
Douglas Muir Quartz-Conglomerate Member is part of the Strathclyde Group
The Douglas Muir Quartz-Conglomerate Member consists mainly of hard, white conglomerates with subordinate pebbly sandstones and a few lenses of purplish grey mudstone up to 30.cm thick. Trough cross-bedding is common in sets from 0.2–1.0.m 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 2.cm, but up to 10.cm in diameter, with some blocks of sandstone up to 15.cm across also present.
Palaeocurrent directions indicate transport of the original sediment towards the south-south-west.
The type section is at the Douglas Muir Quarry in the type area at Douglas Muir (NS 525 746), near Milngavie, Strathclyde where 20 m, being part of the member, are exposed.
Lower and upper boundaries
The base of the member is 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 (Figure 6, Column 4A), as seen at a natural exposure at (NS 5307 7752).
The top of the member is transitional by upward passage by interbedding from conglomerate of the Douglas Muir Quartz-Conglomerate Member to white and pale grey sandstone of the Craigmaddie Muir Sandstone Member, as seen at a natural exposure at (NS 5730 7774).
Incomplete thickness of 20 m at the type locality at Douglas Muir Quarry and up to 70 m maximum elsewhere.
Distribution and regional correlation
Strathclyde. North of the River Clyde and eastwards from the the type area at Douglas Muir (NS 525 746) to the site of the Strathblane–Balmore Tunnel No. 8 Borehole (BGS Registration Number NS57NE/28) (NS 5712 7731), but not in the adjacent parts of 1:50 000 scale Geological Sheet 31W (Airdrie).
Late Visean (Asbian?)
- Paterson, I B, and Hall, I H S.1986.Lithostratigraphy of the late Devonian and early Carboniferous rocks in the Midland Valley of Scotland.Report of the British Geological Survey,Vol. 8, No. 3.
- 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)