The BGS Lexicon of Named Rock Units — Result Details

Tarvie Psammite Formation

Computer Code: TAPS Preferred Map Code: SYMB
Status Code: Full
Age range: Proterozoic Eon (AP) — Proterozoic Eon (AP)
Lithological Description: Well bedded, flaggy, fawn to brown and white quartzose psammite with minor semipelite bands.
Definition of Lower Boundary: Overlies the Ben Wyvis Pelite Formation along the western boundary, where predominant pelites pass into predominantly psammitic lithologies.
Definition of Upper Boundary: Not known.
Thickness: At least 2.5 km thick, up to about 5 km.
Geographical Limits: The northern limit lies immediately west of Struie Hill, on the south side of Dornoch Firth, where it terminates against the faulted Old Red Sandstone (ORS) unconformity. The eastern margin is defined by the ORS unconformity/fault, which continues to the south-west across Strath Rusdale and Glen Glass through Strathpeffer and the eastern end of Strathconon. South of Strathconon it forms a broad outcrop, and extends west to the Orrin Reservoir, continuing south through Strathglass. South and east of Strathglass, the outcrop widens, and the eastern margin extends southwards to Fort Augustus, where it forms the ground between Strathglass and Glen Moriston. The outcrop to the south and west is unclear, but probably does extend further in this direction.
Parent Unit: Loch Eil Group (LEIL)
Previous Name(s): Tarvie Psammitic Group (-3710)
Tarvie Psammite (-2474)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Cnoc na Gearraisich, 4.5 km NNW of Strathpeffer 
Reference(s):
Wilson, D. 1975. Structure and metamorphism of the Ben Wyvis District, Ross-shire. (University of Edinburgh: Unpublished PhD thesis.) 
Johnstone, G S, Smith, D I, and Harris, A L. 1969. The Moinian Assemblage of Scotland. In: Kay, M. (editor). North Atlantic Geology and Continental Drift: A Symposium. Memoirs of the American Association of Petroleum Geologists, Vol. 12, 159-180. 
Holdsworth, R E, Strachan, R A and Harris, A L, 1994. Precambrian rocks in northern Scotland east of the Moine Thrust: The Moine Supergroup in Gibbons, W and Harris, A L (editors). A revised correlation of Precambrian rocks in the British Isles. Special Report of the Geological Society, No.22. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S083 S093 S093 S093