The BGS Lexicon of Named Rock Units — Result Details

Boyd's Burn Lava Member

Computer Code: BDLA Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: The Boyd's Burn Lava Member consists of plagioclase-macrophyric trachybasalt lavas (hawaiite of 'Markle' type). These show a marked variation in the concentration and size of the plagioclase phenocrysts both between and within flows. There are basaltic lapilli-tuffs between the lavas. In the Goat Burn [NS 637 793], a compound flow with three 'flow units' is almost 15 m in thickness. The lavas have a rather slaggy and decomposed nature suggesting that they lie close to their eruptive source, considered to be the Waterhead Centre ('Waterhead Central Volcanic Complex') (Craig, 1980).
Definition of Lower Boundary: The basal plagioclase-macrophyric hawaiite lava of the member is conformable or disconformable on underlying basaltic-trachyandesite (mugearite) of the Lower Lecket Hill Lava Member.
Definition of Upper Boundary: The Boyd's Burn Lava Member is overlain conformably or disconformably by the Upper Lecket Hill Lava Member. The lithological change is mostly to more-felsic lavas, including two basal basaltic-trachyandesite (mugearite) lavas, trachybasalt (hawaiite), and trachyte, but also including plagioclase-microphyric basalt to trachybasalt (of 'Jedburgh' type).
Thickness: 37 to 50 m
Geographical Limits: The member is restricted to the Campsie Block and has a limited geographical extent, (reflecting the proximal character of the lava flows) in the eastern Campsie Fells and westernmost Kilsyth HIlls, north of Glasgow.
Parent Unit: Clyde Plateau Volcanic Formation (CPV)
Previous Name(s): Boyd's Burn Lavas [Obsolete Name and Code: Use BDLA] (-4448)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Boyd's Burn, westernmost Kilsyth Hills, north of Galsgow. The maxium thickness of the member, about 50 m, is developed here, where at least four lavas with proximal-facies characteristics occur and tuffaceous deposits between the lavas are well developed. Craig, 1980. 
Type Area  The eastern Campsie Fells, and westernmost Kilsyth HIlls, north of Glasgow Forsyth et al., 1996, after 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 Unpublished PhD thesis, University of Lancaster.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 Airdrie district. Memoir of the British Geological Survey, Sheet 31W (Scotland). 
Dean, M T, Browne, M A E, Waters, C N and Powell, J H. 2011. A lithostratigraphical framework for the Carboniferous successions of northern Great Britain (onshore). British Geological Survey Research Report, RR/10/007. 165pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S031