The BGS Lexicon of Named Rock Units — Result Details

Schiehallion Quartzite Formation

Computer Code: DBSQ Preferred Map Code: SchQ
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Quartzite, white to grey, fine-grained. The upper half of the formation is especially pure and glassy, with little feldspar or mica. Includes Tempar Dolomitic Member and some beds of conglomerate.
Definition of Lower Boundary: Sharp change from diamictite of Boulder Bed to fine-grained well-bedded quartzite. However, a 10-20m bed of reworked granite diamictite occurs near the base of the Schiehallion Quartzite Formation on Cnocnan Aighean [NN 7292 5551].
Definition of Upper Boundary: Sharp (<10m) change from fine-grained quartzite of Shiehallion Quartzite Formation to dark, layered semipelite and thin-bedded psammite containing 8cm layers of fine-grained garnet-amphibolite.
Thickness: 0 - 800m in Sheet 55W (most thinning is tectonic).
Geographical Limits: From 1km north-east of Forest Lodge, where it pinches out in a tight fold core, southwards to the north shore of Loch Tummel and Loch Kinardochy via Schiehallion to the north-west side of Beinn a Chuallaich. West of this it is cut off by Schiehallion Slide.
Parent Unit: Islay Subgroup (DBIS)
Previous Name(s): Schiehallion Quartzite (*870)
Schichallion Quartzite (-849)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  From Meall nan Aighhean at top of Boulder Bed section via Tempar Dolomitic Member section [NN 725 548] to south side of Schiehallion. 
Reference(s):
Bailey, E B, 1925. Perthshire tectonics: Loch Tummel, Blair Atholl and Glen Shee. Transactions of the Royal Society of Edinburgh, Vol.53, 671-698. 
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). 
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. 
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, 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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S055 S055 S064