The BGS Lexicon of Named Rock Units — Result Details

Carbeth Lava Member

Computer Code: CBTL Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: Mainly plagioclase-macrophyric basalts (Markle type). There are also some plagioclase-microphyric basalts (Jedburgh type) and olivine-clinopyroxene-plagioclase-macrophyric basalts (Dunsapie type) as well as some mugearites near the base.
Definition of Lower Boundary: The Carbeth Lava Member overlies the plagioclase-microphyric basalts (Jedburgh type) of the Auchineden Lava Member.
Definition of Upper Boundary: The Carbeth Lava Member is unconformably overlain by the Greenside Volcaniclastic Member. West of Loch Humphrey [NS 455 760] the member is reduced to one lava flow which is preserved only in isolated patches below the volcaniclastic sedimentary rocks.
Thickness: 0-150 m, thins out to south-west partly due to erosion; thins to c. 80 m in north-east.
Geographical Limits: The Carbeth Lava Member is geographically widespread in the Kilpatrick Hills, north-west of Glasgow, stretching from Strath Blane [NS 560 790] in the north-east to Brown Hill [NS 445 764] in the south-west. The lavas are well exposed around Carbeth and in the Birny Hills.
Parent Unit: Clyde Plateau Volcanic Formation (CPV)
Previous Name(s): Carbeth Lavas (-3907)
Alternative Name(s): none recorded or not applicable
Reference Section  The Carbeth Lava Member was encountered in the Loch Humphrey Borehole beneath the Greenside Volcaniclastic Member and above the Auchineden Lava Member. It is here 20 m thick and consists of Markle-type lavas with some Jedburgh type and some thin bands of tuff. A geological description of the log is available in BGS borehole records. 
Type Area  The lavas are well exposed around Carbeth [NS 527 796] and form prominent scarp features around the Birny Hills [NS 495 770]. Hall et al., 1998. 
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). 
1:50K maps on which the lithostratigraphical unit is found, and map code used: