The BGS Lexicon of Named Rock Units — Result Details

Kilsyth Hills Lava Member

Computer Code: KHLA Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: The Kilsyth Hills Lava Member consists predominantly of plagioclase-macrophyric basalts and trachybasalts (hawaiites of 'Markle' type). The lower of these lavas tend to have sparse and small plagioclase phenocrysts and are transitional to plagiclase-microphyric basalts and trachybasalts (hawaiities of 'Jedburgh' type). Some higher lavas in the sequence are olivine-augite-plagioclase-macrophyric basalts (of 'Dunsapie' type). Also, there is a local intercalation of variably olivine-plagioclase-microphyric basalt lava (of 'Jedburgh' to 'Dalmeny' type). The member is equivalent laterally to the Denny Muir Lava Member which is recognised to the east of the Tak-ma-doon Fault. The lavas were thought by Craig (1980) to have been derived from the Waterhead Centre (`Waterhead Central Volcanic Complex?).
Definition of Lower Boundary: Over most of its outcrop, the base is conformable or disconformable on basaltic-trachyandesite (mugearite) and/or trachybasalt (hawaiite) of the Upper Lecket HIll Lava Member, but towards the south-east, the member rests unconformably on progressively older members, including the Lower Lecket Hill Lava Member, the lower south Campsie lavas (Campsie Lava Member) and the Tappetknowe Lava Member.
Definition of Upper Boundary: The Kilsyth Hills Lava Member occupies summit areas across its outcrop and the top of the member has been eroded.
Thickness: More than 160 m, top eroded
Geographical Limits: The member is restricted to the Campsie Block and specifically to the central Kilsyth Hills west of the Tak-ma-doon Fault, north-east of Glasgow.
Parent Unit: Clyde Plateau Volcanic Formation (CPV)
Previous Name(s): Kilsyth Hills Lavas (-993)
Alternative Name(s): none recorded or not applicable
Type Area  Central Kilsyth Hills, north-east of Glasgow Forsyth et al, 1996, after Craig, 1980 
Reference Section  Crags on the southern flanks of Tomtain Hill, central Kilsyth Hills, north-east of Glasgow Craig, 1980 
Craig, P.M. 1980 The Volcanic Geology of the Campsie Fells area, Stirlingshire. Unpublished PhD thesis, University of Lancaster. 
Forsyth, I H, Hall, I H S and McMillan, A A. 1996. Geology of the Aidrie district. Memoir of the British Geological Survey, Sheet 31W (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used: