The BGS Lexicon of Named Rock Units — Result Details

North Holm Gneiss Formation

Computer Code: NHGN Preferred Map Code: notEntered
Status Code: Full
Age range: Tonian Period (AT) — Tonian Period (AT)
Lithological Description: Strongly gneissose psammite, with muscovite, biotite and garnet; pegmatitic granite veins are common.
Definition of Lower Boundary: Likely overlying the Orknagable Formation (ORKG).
Definition of Upper Boundary: Likely overlain by Kirkaby Gneiss Formation (KIGN).
Thickness: none recorded or not applicable
Geographical Limits: NE Shetland: Unst, Fetlar, Linga.
Parent Unit: Westing Group (WEGP)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
Reference(s):
Krabbendam, M. 2021. A stratigraphic framework for the early Neoproterozoic successions of the Northern Highlands of Scotland. UK Stratigraphic Framework Series. British Geological Survey Open Report, OR/21/072. 86pp. 
Flinn, D. 2014. Geology of Unst, Fetlar and adjacent islands. Memoir of the British Geological Survey, Sheets 131 and part of 130, Scotland. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S131