The BGS Lexicon of Named Rock Units — Result Details

Baron Hill Formation

Computer Code: BAH Preferred Map Code: notEntered
Status Code: Full
Age range: Floian Age (OFL) — Darriwilian Age (ODW)
Lithological Description: Dark to pale grey mudstone, siltstone and sandstone, containing clasts of felsic welded tuff, basalt and basaltic hyaloclastite, locally distrubed. Locally beds of felsic tuff.
Definition of Lower Boundary: Overlies - with likely unconformity - Neoproterozoic rocks of Pen-y-Parc Formation.
Definition of Upper Boundary: Overlain by further Ordovician strata of the Llyn Alaw group (ALAW).
Thickness: At least 300 m thick.
Geographical Limits: Anglesey, near Beaumaris.
Parent Unit: Llyn Alaw Group (ALAW)
Previous Name(s): Baron Hill Rocks [Obsolete Code: Use BAH] (OBH)
Baron Hill Beds (-3189)
Alternative Name(s): none recorded or not applicable
Type Section  Crags alongside track leading through Coed Parc to Baron Hill. Greenly, E, 1919. 
Greenly, E. 1944. The Arvonian rocks of Arvon. Quarterly Journal of the Geological Society, London, 100, 269-287. 
Carney J N et al. 2000. Precambrian rocks of England and Wales. Geological Conservation Review Series. No 20. [Peterborough: Joint Nature Conservation Committee]. 252pp. 
Reedman, A J, Leveridge, B E and Evans, R B. 1984. The Arfon Group (Arvonian?) of North Wales. Proceedings of the Geologists' Association, Vol.95, 313-321. 
Greenly, E. 1919. The Geology of Anglesey, Vol 2. Memoir of the Geological Survey of Great Britain [England and Wales]. [London: H.M.S.O.]. 
Greenly, E. 1946. The Monio-Cambrian interval. Geological Magazine, Vol. 83, 237-240. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E093 E105