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 Grits (-4066)
Glen Lethnot (Grit) Group [Obsolete Name And Code: Use GLGT] (DCGL)
Alternative Name(s): none recorded or not applicable
Stratotypes:
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. 
Reference(s):
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. 
Smith, C G, Goodman, S and Robertson S. 2003. Geology of the Ballater district. Memoir of the British Geological Survey, Sheet 65E (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S065 S066 S067 S066