The BGS Lexicon of Named Rock Units — Result Details

Knocknairshill Member

Computer Code: KKS Preferred Map Code: KKS
Status Code: Full
Age range: Chadian Substage (CI) — Chadian Substage (CI)
Lithological Description: 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).
Definition of Lower Boundary: Interbedded with grey mudstone and dolomitic limestone (cementstone) of the underlying Ballagan Formation. The lower boundary 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.
Definition of Upper Boundary: Boundary of the unit 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 is not exposed. In the Knocknairshill Borehole type section, the member is unconformably overlain by volcaniclastic strata of the Clyde Plateau Volcanic Formation and so the stratigraphical top is not seen.
Thickness: c.130m
Geographical Limits: Greenock district south of the River Clyde to the east and west of Largs Fault Zone, Strathclyde, Scotland.
Parent Unit: Clyde Sandstone Formation (CYD)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Exposed on the coast between Gourock and Clough, Strathclyde, Scotland. Paterson et al., 1990. 
Type Area  Knocknairshill Borehole No.4, BGS Borehole NS37SW/10, at 92.3 m to 222.9 m depth (IGS, 1978), Port Glasgow, Strathclyde, Scotland. The borehole is situated 34m due south from buildings of Knocknairshill. 
Reference(s):
Institute of Geological Sciences, 1978. Institute of Geological Sciences boreholes, 1977. Report of the Institute of Geological Sciences, No.78/21. 
Paterson, I B, Hall, I H S & Stephenson, D. 1990. Geology of the Greenock district: Memoir for 1:50000 geological sheet 30W and part of sheet 29E (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:
S003 S030