The BGS Lexicon of Named Rock Units — Result Details

Blair Atholl Subgroup

Computer Code: DABA Preferred Map Code: BlAt
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Semipelite and pelite, much of it graphitic; interbedded with limestone units, the lower limestones typically graphitic, the uppermost typically dolomitic
Definition of Lower Boundary: At top of Ballachulish Subgroup; generally at the transition from banded semipelite and limestone to more graphitic pelite with limestone beds.
Definition of Upper Boundary: At base of Islay Subgroup; generally transitional over a few metres where pale dolomitic limestone passes into psammite or quartzite with beds or larger units of diamictite.
Thickness: c.300 to 600m (but locally tectonically thinned to 50m)
Geographical Limits: Islay; Lismore; Appin; also a strip from near Blair Atholl to the Moray Firth coast at Sandend Bay (between Cullen and Portsoy). Also occurs in Ireland around Glencolumbkille and Falcarragh (Donegal) and in Connemara (Co. Galway).
Parent Unit: Appin Group (APP)
Previous Name(s): BLAIR ATHOLL SERIES
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  (Local). Traverse running south from Allt Leathan, 800m south of Lochan an Daim. 
Partial Type Section  East end of Sandend Bay: lower part of succession partly obscured by beach deposits and ?Middle Devonian breccia: cut off to east by north west-south east fault. 
Type Area  In vicinity of Blair Atholl; bounded to west by Loch Tay Fault and to east by Killiecrankie Slide. 
Reference(s):
Barrow, G, Grant Wilson, J S and Cunningham Craig, E H, 1905. The geology of the country around Blair Atholl, Pitlochry and Aberfeldy. Memoir of the British Geological Survey, Scotland (Sheet 55). 
Harris, A L and Pitcher, W S, 1975. The Dalradian Supergroup. 52-75 in Harris, A L, Shackleton, R M, Watson, J, Downie, C, Harland, W B and Moorbath, S. A correlation of the Precambrian rocks in the British Isles. Special Report of the British Geological Society, London, No.6. 
Bailey, E B, 1925. Perthshire tectonics: Loch Tummel, Blair Atholl and Glen Shee. Transactions of the Royal Society of Edinburgh, Vol.53, 671-698. 
Bailey, E B and McCallien, W J, 1937. Perthshire tectonics: Schiehallion to Glen Lyon. Transactions of the Royal Society of Edinburgh, Vol.59, 79-117. 
Harris, A L, Haselock, P J, Kennedy, M J and Mendum, J R, 1994. The Dalradian Supergroup in Scotland, Shetland and Ireland. 33-53 in Gibbons, W E and Harris, A L (editors). A revised correlation of Precambrian rocks in the British Isles. Special Report of the Geological Society, London, No.22. 
Stephenson, D and Gould, D , 1995. British Regional Geology: the Grampian Highlands (4th edition). (London: HMSO for the British Geological Survey), 67-68. 
Treagus, J E. 2001. Solid geology of the Schiehallion district. Memoir of the British Geological Survey, Sheet 55W (Scotland). 
Treagus, J E and King, G, 1978. A complete Lower Dalradian succession in the Schiehallion district, central Perthshire. Scottish Journal of Geology, Vol.14, 157-166. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S019 S027 S044 S044 S045 S053 S055 S055 S056 S064 S065 S065 S075 S075 S085 S086 S096 S036 S096 S053