The BGS Lexicon of Named Rock Units — Result Details

Creag Dhubh Psammite Formation

Computer Code: CDHP Preferred Map Code: notEntered
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Grey flaggy quartzo-feldspathic psammite with micaceous psammite interlayers grading into micaceous pelitic tops, including muscovite and biotite. Psammites 10 to 40cm thick are common, thinner near the base; amalgamated psammites up to 6m thick are known. Semipelites/pelites are usually about 1cm thick but locally up to 20cm thick.
Definition of Lower Boundary: Top of the Torr na Truim Semipelite Formation, where predominantly schistose semipelite is overlain by the flaggy bedded, predominantly psammitic succession belonging to the Creag Dhubh Psammite Formation.
Definition of Upper Boundary: Base of the Creag na Sanais Semipelite Formation, where predominantly gneissose semipelite overlies the psammitic succession belonging to the Creag Dhubh Psammite Formation.
Thickness: c.700m +
Geographical Limits: Southwest of Newtonmore, from Glen Banchor southwards to the Ericht-Laidon Fault
Parent Unit: Corrieyairack Subgroup (GRCO)
Previous Name(s): Part Of The Moine Psammites (-4416)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Outcrops around Creag Dhubh and eastwards to the base of Creag Ruadh. Leslie, A G et al., BGS Internal Report IR/03/048 
Partial Type Section  Outcrops between Cruban Beag and Creag na Sanais (top of the Formation) Leslie, A G et al., BGS Internal Report IR/03/048 
Reference(s):
Leslie, A G, Krabbendam, M and Smith, R A, 2003. Progress Report on the Geology of 1:50 k Sheet 64W (Newtonmore) British Geological Survey Internal Report, IR/03/048. 23pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable