Gourock Sandstone Member
Gourock Sandstone Member (GKA), South of the River Clyde, Carboniferous, Midland Valley of Scotland
Gourock Sandstone Member is part of the Clyde Sandstone Formation.
From the town of Gourock on the south side of the Clyde Estuary. Previously known as the Gourock Formation.
The Gourock Sandstone Member comprises white, cross-bedded sandstone with thin beds of red-brown, silty mudstone, and nodules and beds of pedogenic limestone. It is distinguished from other units of the Clyde Sandstone Formation by the presence of thicker beds of sandstone, a lesser proportion of mudstone and less abundant calcareous nodules (Paterson and Hall, 1986; BGS, 1990). Paterson et al. (1990) described the member as comprising thick multistorey bodies of white pebbly sandstone.
The type area is at (NS 205 761) on 1:50 000 scale Geological Sheet Scotland 29E.
Lower and upper boundaries
The lower boundary of the member with the underlying Knocknairshill Member (Figure 6, Column 4B) is mapped in the vicinity of Gourock Golf Course (NS 2230 7630). It is recognised by the presence of thick beds of white pebbly sandstone in the overlying Gourock Sandstone Member, but the boundary itself is not exposed.
The upper boundary is not seen but it is presumed to be overlain by sandstone and mudstone strata of the Broadlee Glen Sandstone Member (Paterson and Hall, 1986), which distinctively include plant debris and beds of grey mudstone (BGS, 1990).
About 300 m.
Distribution and regional correlation
The Greenock district south of the River Clyde, and also west of the Largs Fault Zone, Strathclyde.
- 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
- British Geological Survey. 1990. Greenock. Scotland Sheet 30W. Solid. 1:50.000. (Keyworth, Nottingham: British Geological Survey.)
- Paterson, I B, Hall, I H S, and Stephenson, D. 1990. Geology of the Greenock district.Memoir of the British Geological Survey, Sheet 30W part 29E (Scotland)