Knocknairshill Member (KKS), South of the River Clyde, Carboniferous, Midland Valley of Scotland
Knocknairshill Member is part of the Clyde Sandstone Formation.
From Knocknairshill, Port of Glasgow, Strathclyde.
Mainly white or pale red cross-bedded sandstone with beds of red-brown silty mudstone; nodules and beds of pedogenic limestone (Paterson and Hall, 1986). The member comprises well-developed upward-fining fluvial cycles including pedogenic carbonate (‘cornstone’) within the mudstone deposits in most cycles (Paterson and Hall, 1986; Paterson et al., 1990; see also IGS, 1978).
A type section is exposed on the coast between Gourock and Clough, Strathclyde (NS 2340 7726 to 2082 7617). An additional section occurs in the Knocknairshill BGS Borehole No. 4 (BGS Registration Number NS37SW/10) (NS 3056 7438) from 92.3 to 222.9 m depth (see Paterson et al., 1990).
Lower and upper boundaries
The member at its lower boundary is interbedded with grey mudstone and dolomitic limestone (‘cementstone’) of the underlying Ballagan Formation (Figure 6, Column 4B). The base is picked where dolomitic limestone and grey mudstone beds are absent, and at the base of the first thick interval of sandstone containing medium, fining-upward beds of brownish grey, fine-grained sandstone and reddish brown, silty mudstone.
The upper boundary of the member with the white cross-bedded sandstones of the overlying Gourock Sandstone Member is mapped in the vicinity of Gourock Golf Course (NS 2230 7630) but it is not exposed. In the Knocknairshill BGS Borehole No. 4 (see above) the member is unconformably overlain by volcaniclastic strata of the Clyde Plateau Volcanic Formation.
The member is 130.58 m thick in the Knocknairshill BGS Borehole No. 4 (see above).
Distribution and regional correlation
The Greenock district south of the River Clyde to east and 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
- 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)
- Institute of Geological Sciences. 1978. Institute of Geological Sciences boreholes 1977. Report of the Institute of Geological Sciences, No. 78/21