The BGS Lexicon of Named Rock Units — Result Details

Baston Burn Lava Member

Computer Code: BAST Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: The Baston Burn Lava Member consists predominantly of plagioclase-macrophyric basalt lavas (of 'Markle' type) with a few microporphyritic lavas, or microporphyritic components of composite lavas (of 'Jedburgh' type).
Definition of Lower Boundary: In the northern Touch Hills, and north-eastern Gargunnock Hills, the basal macroporphyritic lava of the member is conformable or disconformable on a trachybasalt lava of the Slackdown Lava Member. Farther west, where the trachybasalt is absent, the basal lava of the Baston Burn Lava Member is a transitional plagioclase-macrophyric to plagioclase-microphyric basalt which overlies conformably or disconformably a microporphyritic basalt of the Slackdown Lava Member.
Definition of Upper Boundary: In the northern Touch Hills and north-eastern Gargunnock Hills, the Baston Burn Lava Member is overlain unconformably by the Spout of Ballochleam Lava Member, and the Baston Burn Lava Member is progressively truncated towards the west. The lithological change is to microporphyritic basalt (of 'Jedburgh' type). In the north-western Gargunnock Hills, the Baston Burn Lava Member is overlain unconformably by the Slackgun Volcaniclastic Member, and the lithological transition is to weathered basalt ('bole') and well-bedded tuff.
Thickness: 9-67m
Geographical Limits: The member is restricted to the northern Fintry Hills and the north-eastern Gargunnock Hills.
Parent Unit: Clyde Plateau Volcanic Formation (CPV)
Previous Name(s): Baston Burn Group (-40)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Gargunnock Burn, central northern Gargunnock Hills, north-east of Glasgow Francis et al, 1970 
Type Area  In the northern Touch Hills and Gargunnock Hills, north-east of Glasgow. The member weathers to form a prominent and wide step in the cliffs above the Slackdown Lava Member, extending north-east from the north side of Lees HIll [NS 6580 9120] to Standmilane Craig [NS 670 918] and Black Craig [NS 685 924] and east to the Gargunnock Burn ([NS 7073 9292] to [NS 7060 9267]) and Baston Burn [NS 7351 9352]. Francis et al, 1970 
Reference(s):
Francis, E H, Forsyth, I H, Read, W A and Armstrong, M. 1970. The geology of the Stirling district. Memoir of the Geological Survey of Great Britain, Sheet 39 (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S039