The BGS Lexicon of Named Rock Units — Result Details

Gleniffer Lava Member

Computer Code: GLLA Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: Distinctive olivine-bearing plagioclase-macrophyric basalts (Markle type). Characterised by lava flows with abundant, platy phenocrysts of plagioclase up to 25mm long and microphenocrysts of red-brown olivine. A massive flow of plagioclase-microphyric basalt (Jedburgh type) forms the base of the member at Linn Well [2475 6605]. Lavas are interbedded with volcaniclastic sedimentary rocks at the base of the member.
Definition of Lower Boundary: The Gleniffer Lava Member is underlain by the sedimentary rocks of the Glenburn Volcaniclastic Member to the north and east of Brownside Braes [2485 6605].
Definition of Upper Boundary: The Gleniffer Lava Member is overlain and may be cut out or overlapped, by the mafic basalts of the Sergeantlaw Lava Member around Sergeantlaw [2455 6597] and to the east of Middleton [2445 6579], and to the west of Barcraigs Reservoir [239 657] and Walls Hill [241 659]. The Gleniffer Lava Member may thin to the east .
Thickness: none recorded or not applicable
Geographical Limits: The Gleniffer Lava Member crops out in the Beith - Barrhead Hills, to the east of Barcraigs Reservoir [NS 39 57] and is faulted against the Kirkwood Formation and Lawmuir Formation in the north, to the north of High Burnside [NS 42 60]. It extends eastwards through Gleniffer Braes [NS 450 607] to Brownside Braes [NS 485 605].To the south the unit is faulted against the Upper Limestone Formation at Loch Libo [NS 465 556] and the Limestone Coal Formation by the Lugton Water Fault.
Parent Unit: Clyde Plateau Volcanic Formation (CPV)
Previous Name(s): 'Gleniffer Lavas' (-2207)
Alternative Name(s): none recorded or not applicable
Type Area  The Gleniffer Lava Member crops out in a prominent scarp along the north side of Gleniffer Braes to Brownside Braes. Hall et al. 1998 
Monro, S K. 1999. Geology of the Irvine District. Memoir of the British Geological Survey, Sheet 22W and part of 21E (Scotland). 
Hall, I H S, Browne, M A E and Forsyth, I H. 1998. Geology of the Glasgow district. Memoir of the British Geological Survey, Sheet 30E (Scotland). 
Richey, J E, Anderson, E M, and Macgregor, A G. 1930.The geology of north Ayreshire. Memoir of the Geological Survey of Great Britain. 
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). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S030 S030 S022 S022