The BGS Lexicon of Named Rock Units — Result Details

Largs Lava Member

Computer Code: LGLA Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: Olivine-microphyric basalt lavas (Dalmeny type) with a few flows of clinopyroxene-olivine-microphyric basalt (Hillhouse type). Some clinopyroxene-olivine-macrophyric basalt (ankaramite or Craiglockhart type) intercalated in upper part of sequence.
Definition of Lower Boundary: The Largs Lava Member overlies the Noddsdale Volcaniclastic Member, as was proved in the Largs Borehole [NS 2158 5936].
Definition of Upper Boundary: Lavas of the Largs Lava Member are more mafic than those of the overlying Greeto Lava Member with the boundary defined by the petrographic change from olivine-microphyric basalts (Dalmeny type) of the Largs Lava Member to the overlying plagioclase-phyric basalts and hawaiites (Jedburgh and Markle types) of the Greeto Lava Member.
Thickness: Up to 130m.
Geographical Limits: Scarp slope east of Noddsdale Water from Largs [NS 20 59] to the Murishiel Fault [NS 23 65], east side of Knockencorsan Hill [NS 24 67]. South of Largs on the lower slopes of Douglas Park to the A760 road [NS 21 57].
Parent Unit: Clyde Plateau Volcanic Formation (CPV)
Previous Name(s): Largs Lavas (-1655)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Exposed in a major scarp on the east side of Noddsdale, to the south of the Muirshiel Fault, traced north along the east side of Noddsdale Water; on the east side of Knockencorsan Hill [NS 24 67] and in the Rotten Burn [NS 252 682]. 
Reference(s):
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). 
Johnstone, G S. 1965. The volcanic rocks of the Misty Law-Knockside Hills district, Renfrewshire. Bulletin of the Geological Survey of Great Britain. No. 22. pp 53-64. 
Richey, J E. 1928. The north Ayrshire sequence of Calciferous Sandstone volcanic rocks. Transactions of the Geological Society of Glasgow. 18. pp 247-255. 
Monro, S K. 1999. Geology of the Irvine District. Memoir of the British Geological Survey, Sheet 22W and part of 21E (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S030