The BGS Lexicon of Named Rock Units — Result Details

Nochty Semipelite And Limestone Formation

Computer Code: NSAL Preferred Map Code: SYMB
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Striped/banded semipelite and pelite, part calcareous, with numerous limestone bands. Calc-silicate lenticles common in north. Thin dolomite bands also. South of River Don flaggy semipelites and micaceous psammites dominant and carbonate rare.
Definition of Lower Boundary: Rapid transition downwards to banded psammite-semipelite sequence (Ladder Hills Formation); south of River Don overlies Tornahaish Formation semipelite with carbonate.
Definition of Upper Boundary: Lower limit of quartzite of Kymah Quartzite Formation or gradation to banded psammite-semipelite sequence (+ volcaniclastic horizons) of Ladder Hills Formation.
Thickness: Maximum 1310m. Probably duplicated by folding - more likely thickness c. 500m.
Geographical Limits: Ladder Hills area. Extends from Kymah Burn section southwest to Littleglen Burn and Water of Nochty, then SSE to Ernan Water, Donside and Glen Fenzie (Sheet 75E only).
Parent Unit: Islay Subgroup (DBIS)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Reference Section  Ernan Water section southeast of Rock Ernan and west of Craig Aighean. 
Type Section  Lower part of Allt Slochd Chaimbeil and upper part of Water of Nochty (upstream of junction with Allt Chuirn Deirg). 
Reference Section  Upper part of Allt na Gaothain upstream of A939 road. 
Memoir of the British Geological Survey, Sheet 75, in preparation. 
1:50K maps on which the lithostratigraphical unit is found, and map code used: