| Computer Code: |
BRAI |
Preferred Map Code: |
BRAI |
| Status Code: |
Full |
| Age range: |
Pridoli Epoch (SO)
— Lochkovian Age (DO) |
| Lithological Description: |
Thin basal bed of basaltic tuff overlain by flows of highly altered biotite-trachyte and ?biotite-andesite. |
| Definition of Lower Boundary: |
At base of impersistent bed of basaltic tuff, which is possibly unconformable on olivine basalt of the Fairmilehead Member. |
| Definition of Upper Boundary: |
At top of highest flow of trachyte or biotite andesite where overlain by pyroxene andesite of the Blackford Hill Member. |
| Thickness: |
140m |
| Geographical Limits: |
From Comiston Road [NT 242 695] in the west to Alnwickhill Camp [NT 264 690] in the east, and from Mortonhall Golf Club House [NT 245 693] in the south to the Hermitage of Braid [NT 260 703] in the north. |
| Parent Unit: |
Pentland Hills Volcanic Formation (PDH)
|
| Previous Name(s): |
Fairmilehead, Braids and Blackford [Obsolete Name and Code: Use BRAI, FAI, BLCK]
(-1989)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Braid Hills. |
| Reference(s): |
| Mitchell, G H. 1962. The geology of the neighbourhood of Edinburgh. (Explanation of Sheet 32) Third Edition. (Reprinted 1980). Memoir of the Geological Survey of Great Britain (Scotland). |
| Mykura, W, 1960. The Lower Old Red Sandstone igneous rocks of the Pentland Hills. Bulletin of the Geological Survey of Great Britain, No.16, 131-155. |
| Peach, B N, Clough, C T, Hinxman, L W, Grant Wilson, J S, Crampton, C B, Maufe, H B and Bailey, E B, 1910. The geology of the Neighbourhood of Edinburgh (2nd edition). Memoir of the Geological Survey of Scotland, Sheet 32 (Scotland). |
| Thirlwall, M F, 1988. Geochronology of Late Caledenian magmatism in northern Britain. Journal of the Geological Society, Vol.145, 951-967. |
| Cameron, I B, and Stephenson, D. 1985. British Regional Geology: The Midland Valley of Scotland (3rd Edition). (London: HMSO for British Geological Survey.) |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
S032
|
