The BGS Lexicon of Named Rock Units — Result Details

Tarff Banded Formation

Computer Code: TARF Preferred Map Code: T
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Interbedded semipelite and micaceous psammite, contains distinctive garnets with snowball and spiral inclusion patterns in semipelites near shear zones. Quartzite and pelite interbeds, notably in basal part.
Definition of Lower Boundary: Conformable transition from underlying Glen Doe Psammite to semipelite/micaceous psammite-dominated sequence. Locally marked by appearance of impersistent quartzite beds and striped psammites.
Definition of Upper Boundary: Not seen - faulted and sheared with Glen Buck Pebbly Psammite Formation.
Thickness: Minimum 2.7km up to c. 3km.
Geographical Limits: South-western Monadhliath Mountains in Central Highland of Scotland (SE of Great Glen).
Parent Unit: Corrieyairack Subgroup (GRCO)
Previous Name(s): none recorded or not applicable
Alternative Name(s): Ardair Semipelite Formation
Monadhliath Semipelite Formation
Type Area  North of Coire Odhar Beag, to Glen Tarff. 
Partial Type Section  Basal contact at Carn a' Chuillin. 
Key, R M, Clark, G C, May, F, Phillips, E R, Chacksfield, B C and Peacock, J D, 1997. Geology of the Glen Roy district. Memoir of the British Geological Survey, Sheet 63W [Scotland]. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S063 S073