| Computer Code: |
BMLA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Arundian Substage (CJ)
— Asbian Substage (CR) |
| Lithological Description: |
The Black Mount Lava Member consists predominantly of plagioclase-microphyric basalt lavas (of 'Jedburgh' type) with subordinate basaltic-trachyandesite (mugearite) lavas. The microporphyritic basalt lavas are variably albitised, slaggy, vesicular, and platy jointed and are locally transitional to a partly plagioclase-macrophyric lithology. |
| Definition of Lower Boundary: |
The basal plagioclase-microphyric basalt of the Black Mount Lava Member is apparently conformable or disconformable on plagioclase-macrophyric basalt lava of the Gargunnock Hills Lava Member. |
| Definition of Upper Boundary: |
The Black Mount Member is overlain by plagioclase-macrophyric basalt lava (of 'Markle' type) of the Touch House Lava Member. The lithological transition is from plagioclase-microphyric to plagioclase-macrophyric basalt. |
| Thickness: |
More than 24 m |
| Geographical Limits: |
The member is restricted to the eastern Touch Hills, north-east of Glasgow. These rocks crop out from the west side of Black Mount [NS 7391 9175] to near Seton in the north-east [NS 7600 9327] and Garter Wood in the east [NS 7652 9189]. |
| Parent Unit: |
Clyde Plateau Volcanic Formation (CPV)
|
| Previous Name(s): |
Black Mount Group
(-68)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
The south side of Touch Burn gorge, north-east Touch Hills, north-east of Glasgow. Francis et al., 1970. |
| Type Area |
In the eastern Touch Hills, north-east of Glasgow. Francis et al., 1970. |
| 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. |
| 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
|
