| Computer Code: |
SLA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Arundian Substage (CJ)
— Asbian Substage (CR) |
| Lithological Description: |
Olivine-microphyric basalt (Dalmeny type) and olivine-clinopyroxene-plagioclase-macrophyric basalt (Dunsapie type). In the closure of the Beith anticline the basal flow of the member is a distinctive clinopyroxene-olivine-macrophyric basalt (ankaramite or Craiglockhart type). In Boylestone Quarry [NS 495 597] hydrothermal veins and cavities contain a wide variety of minerals including calcite, analcime, prehnite, heulandite, bowlingite, thompsonite and natrolite. Native copper, cuprite and malachite are also found. |
| Definition of Lower Boundary: |
The Sergeantlaw Lava Member overlies the plagioclase-macrophyric basalts (Markle type) of the Gleniffer Lava Member. South of Wester Gavin [NS 380 589] the mafic basalts of the Sergeantlaw Lava Member appear to rest upon volcaniclastic sediments and it is possible that in this area the underlying Glenliffer Lava Member has been overlapped. To the north of Harelaw Reservoir [NS 485 590] the Sergeantlaw Lava Member appears to cut out or overlap most of the Gleniffer Lava Member. |
| Definition of Upper Boundary: |
Resting upon the Sergeantlaw Lava Member and forming a broad dip slope outcrop south of Muirdykes [NS 395 591] are the plagioclase-macrophyric basalts (Markle type) and olivine-clinopyroxene-plagioclase basalts (Dunsapie type) of the Fereneze Lava Member. |
| Thickness: |
Not stated. |
| Geographical Limits: |
The Sergeantlaw Lava Member crops out in the Beith - Barrhead Hills to the north and south of Barcraigs Reservoir [NS 39 57]. It is well seen between Townhead of Threepwood [NS 39 55] and Gillies Hill [NS 38 54] and forms scarp features around Walls Hill [NS 412 589]. It is also present in the area between Sergeant Law [NS 455 596] and Greenfieldmuir [NS 456 583] and in the Lochliboside Hills [NS 450 575]. |
| Parent Unit: |
Clyde Plateau Volcanic Formation (CPV)
|
| Previous Name(s): |
Sergeantlaw Lavas [Obsolete Name and Code: Use SLA]
(-3681)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Well seen in its type area between Sergeantlaw [NS 455 596] and Greenfieldmuir [NS 456 583] (Hall et al., 1998). |
| Reference Section |
Well seen in the area between Townhead of Threepwood [NS 39 55] and Gillies Hill [NS 38 54] (Monro, 1999). |
| Reference(s): |
| Monro, S K. 1999. Geology of the Irvine District. Memoir of the British Geological Survey, Sheet 22W and part of 21E (Scotland). |
| Paterson, I B, Hall, I H S and Stephenson, D. 1990. Geology of the Greenock district: Memoir for 1:50000 geological sheet 30W and part of sheet 29E (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). |
| Richey, J E, Anderson, E M, and Macgregor, A G. 1930.The geology of north Ayreshire. Memoir of the Geological Survey of Great Britain. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
S022
S022
S030
S030
|
