The BGS Lexicon of Named Rock Units — Result Details

Pitlochry Schist Formation

Computer Code: DCPS Preferred Map Code: PitS
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Semipelite dominant with interbedded pelite, micaceous psammite and volcaniclastic rocks (Green Beds), and containing minor pebbly psammite. Metamorphosed to garnet-mica schist in type area.
Definition of Lower Boundary: Change from silty limestone at top of Loch Tay Limestone to dominantly semipelitic and pelitic rocks.
Definition of Upper Boundary: Change from dominantly semipelitic rocks to dominantly psammitic rocks (not seen in Sheet 55W). In parts of the outcrop outwith Sheet 55W, the change coincides with the main volcaniclastic unit.
Thickness: 300 - 500m (estimated 300+m in Sheet 55W); not mapped separately in Sheet 55E, but transition to Ben Ledi Grit or equivalent probably occurs 300 - 500m above base of Southern Highland Group, close to main 'Green Beds' unit.
Geographical Limits: From Glen Brerachan [NO 01 63], 9km north-east of Pitlochry, south-westwards through Pitlochry [NN 94 58] to Kenmore [NN 77 45] and at least as far as Loch Tay Fault in Sheets 46 and 47. Also small outlier west of Glen Doll Fault [NO 23 78].
Parent Unit: Southern Highland Group (SOHI)
Previous Name(s): Pitlochry Schist (-2146)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  (Lower part of Formation). Keltney Burn from boundary with Loch Tay Limestone to confluence with Allt Coire Pheiginn, downstream as far as hotel at Coshieville. 
Partial Type Section  (Upper part of Formation). Camaserney Burn from confluence with Ruith Mhuilinn downstream to include 'Green Beds' at Camaserney. 
Reference(s):
Treagus, J E. 2001. Solid geology of the Schiehallion district. Memoir of the British Geological Survey, Sheet 55W (Scotland). 
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. 
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). 
Stephenson, D and Gould, D , 1995. British Regional Geology: the Grampian Highlands (4th edition). (London: HMSO for the British Geological Survey), 67-68. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S055 S065 S047 S046 S055 S046 S046