The BGS Lexicon of Named Rock Units — Result Details

Ruthven Semipelite Formation

Computer Code: RUVN Preferred Map Code: R
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Coarsely foliated, migmatic semipelite and pelite with subordinate striped psammites with bands of calcsilicate rock. Minor amphibolite pods and lenses.
Definition of Lower Boundary: Marked lithological contact with underlying arkosic psammites of the Glenshirra Subgroup, commonly attenuated locally, possibly unconformable.
Definition of Upper Boundary: Poorly exposed, incoming of well-bedded psammites [turbiditic] of the Loch Laggan Psammite Formation.
Thickness: In excess of 200 m - difficult to estimate due to complex fold patterns.
Geographical Limits: Strath Nairn and north-western part of Monadhliath Mountains, Central Highlands, 1:50 K sheets 73E and 74W.
Parent Unit: Corrieyairack Subgroup (GRCO)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Reference Section  Roches moutonees immediately northeast of Achneim House, Strath Nairn. 
Type Area  Prominent ice-sculptured crags of Craig Ruthven and Stac Gorm on the southern shores of Loch Ruthven. 
Reference Section  Crags some 200 m - 300 m south and east of Milton Farm, Strath Nairn = upper parts of formation. 
none recorded or not applicable
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S074 S073 S073