| Computer Code: |
HHLA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Arundian Substage (CJ)
— Asbian Substage (CR) |
| Lithological Description: |
The Holehead Lava Member consists mainly of plagioclase-macrophyric basalts and trachybasalts (basalts to hawaiites of 'Markle' type), characterised by the presence of variable amounts of generally relatively small plagioclase macrophenocrysts. In addition, one lava of transitional trachybasalt to mugearite composition is exposed in the middle of lava sequence. The flows tend to be relatively thin with slaggy tops and locally rubbly bases. The lavas were thought by Craig (1980) to have been derived from the Waterhead Centre ('Waterhead Central Volcanic Complex'). |
| Definition of Lower Boundary: |
The basal plagioclase-macrophyric basalt, and or trachybasalt (hawaiite), is conformable or disconformable on basaltic-trachyandesite (mugearite) of the Fin Glen Lava Member. |
| Definition of Upper Boundary: |
The Holehead Lava Member occupies summit areas across its outcrop and the top of the member has been eroded. |
| Thickness: |
More than 100 m, top eroded. |
| Geographical Limits: |
The member is restricted to the Campsie Block and has a limited geographical extent in the Central Campsie Fells, north of Glasgow. |
| Parent Unit: |
Clyde Plateau Volcanic Formation (CPV)
|
| Previous Name(s): |
Holehead Lavas [Obsolete Name and Code: Use HHLA]
(-2237)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Central Campsie Fells, north of Glasgow. Forsyth et al., 1996, after Craig, 1980. |
| Reference Section |
Aldesssan Burn, central Campsie Fells, north of Glasgow. Craig, 1980. |
| Reference(s): |
| Craig, P M. 1980. The Volcanic Geology of the Campsie Fells area, Stirlingshire. Unpublished PhD thesis, University of Lancaster. |
| Forsyth, I H, Hall, I H S and McMillan, A A. 1996. Geology of the Airdrie district. Memoir of the British Geological Survey, Sheet 31W (Scotland). |
| 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: |
|
S031
S030
|
