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 Beds (-3189)
Baron Hill Rocks [Obsolete Code: Use BAH] (OBH)
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. 1946. The Monio-Cambrian interval. Geological Magazine, Vol. 83, 237-240. 
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.]. 
Carney J N et al. 2000. Precambrian rocks of England and Wales. Geological Conservation Review Series. No 20. [Peterborough: Joint Nature Conservation Committee]. 252pp. 
Greenly, E. 1944. The Arvonian rocks of Arvon. Quarterly Journal of the Geological Society, London, 100, 269-287. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E093 E105