| 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 [Obsolete Name and Code: Use CBTL]
(-3907)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| 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. |
| Reference(s): |
| 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. |
| 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: |
|
S030
|
