The BGS Lexicon of Named Rock Units — Result Details

Langhill Lava Member

Computer Code: LHLA Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: The Langhill Lava Member consists of four lavas of typically fine-grained, platy-jointed basaltic-trachyandesite (mugearite) with a total thickness of 35 m. The only exposures are in the River Carron [NS 773 845], 500 m north-east of Langhill. The lowest lava is relatively coarse grained and is about 15 m thick, with well-developed columnar jointing. The other lavas are very fine grained and intensely jointed. One at least of these has an autobrecciated base, consisting of buckled and disrupted tabular blocks of the lava.
Definition of Lower Boundary: The member overlies plagioclase-microphyric trachybasalt of the Campsie Lava Member, but the nature of the contact is unknown.
Definition of Upper Boundary: The Langhill Lava Member is overlain by the Gargunnock Hills Lava Member, but the nature of the contact is unknown. The lithological change is to mostly plagioclase-macrophyric basalt or hawaiite (of 'Markle type') with some microporphyritic basalts (of 'Jedburgh' and 'Dalmeny' types).
Thickness: 35 m
Geographical Limits: The member is restricted to the Campsie Block (Forsyth et al, 1996) and specifically to the eastern part of the Kilsyth Hills, north-east of Glasgow. These rocks mostly crop out on the northern side of the Carron Glen (between [NS 7750 8442] and [NS 7616 8539]), with the outcrop extending locally to the base of the valley [NS 7739 8450] and onto the southern side [NS 7709 6446].
Parent Unit: Clyde Plateau Volcanic Formation (CPV)
Previous Name(s): Langhill Lavas (-2902)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  The eastern part of the Kilsyth Hills, north-east of Glasgow Forsyth et al., 1996, after Craig, 1980 
Reference Section  River Carron, eastern Kilsyth Hills, north-east of Glasgow Craig, 1980 
Reference(s):
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 Unpublished PhD thesis, University of Lancaster.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:
S031