The BGS Lexicon of Named Rock Units — Result Details

Moel Hebog Sandstone Member

Computer Code: MOH Preferred Map Code: MoH
Status Code: Full
Age range: Soudleyan Substage (OY) — Longvillian Substage (OL)
Lithological Description: Well-bedded microconglomerates locally containing larger clasts of felsic tuff, coarse-grained sandstones and subordinate thinner silty sandstones. Many sedimentary structures including large-scale cross-bedding, ripple lamination, grading and channels as well as convolute lamination and slump structures.
Definition of Lower Boundary: Conformable within the Cwm Eigiau Formation.
Definition of Upper Boundary: Conformably overlain by the felsic ash-flow tuffs of the Pitts Head Tuff Formation.
Thickness: To 250m
Geographical Limits: Snowdonia, North Wales.
Parent Unit: Cwm Eigiau Formation (CEI)
Previous Name(s): Gorllwyn Grits (-3558)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Eastern flanks of Moel Hebog, Snowdonia, North Wales. Howells, M F and Smith, M. 1997. 
Reference(s):
Howells, M F and Smith, M. 1997. Geology of the country around Snowdon. Memoir of the British Geological Survey, Sheet 119 (England and Wales). (London: The Stationery Office). 104pp. 
Shackleton, R M. 1959. The stratigraphy of the Moel Hebog district between Snowdon and Tremadoc. Liverpool and Manchester Geological Journal, Vol.2, 216-252. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E119