The BGS Lexicon of Named Rock Units — Result Details

Glen Lethnot Grit Formation

Computer Code: GLGT Preferred Map Code: litho
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Mixed psammite, semipelite and pelite. Psammites typically gritty. Pelites include types rich in staurolite and muscovite, and some are also kyanite-bearing. Schists rich in iron-ore minerals form mappable units in places. Beds of quartzite with specks of green mica occur rarely near the base of the Formation.
Definition of Lower Boundary: Gradational transition from Glen Effock Schist Formation marked by incoming of silvery muscovite-rich pelite, increase in proportion of gritty psammite and decrease in proportion of green feldspathic semipelite.
Definition of Upper Boundary: Not seen: faulted against Highland Border Complex.
Thickness: At least 3000m indicated in Glen Esk; tectonic thickening probably less than in Glen Effock Schist Formation.
Geographical Limits: Occurs in the southeast corner of Sheet 65E and the southern border of Sheet 66W from White Hill (NO 402 731) to Bannock Hill (NO 610 760).
Parent Unit: Southern Highland Group (SOHI)
Previous Name(s): Glen Lethnot (Grit) Group [Obsolete Name And Code: Use GLGT] (DCGL)
Glen Lethnot Grits (-4066)
Alternative Name(s): none recorded or not applicable
Type Area  Stream section in West Water (Glen Lethnot) from Waterhead to southern boundary of Sheet 66W south of Stonyford; also adjacent Craigs of Stonyford. 
Smith, C G, Goodman, S and Robertson S. 2003. Geology of the Ballater district. Memoir of the British Geological Survey, Sheet 65E (Scotland). 
Harte, B, 1979. The Tarfside succession and the structure and stratigraphy of the eastern Scottish Dalradian rocks. "In" Harris, A L, Holland, C H and Leake, B E. Geological Society of London Special Publication No.8, p.221-228. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S065 S066 S067 S066