The BGS Lexicon of Named Rock Units — Result Details

Caerfai Bay Shales Formation

Computer Code: CFBS Preferred Map Code: CaB
Status Code: Pending Upgrade
Age range: Comley Series (EC) — Comley Series (EC)
Lithological Description: Purplish red mudstones with some siltstone beds and laminae, cross-bedded in lower part and with units of crystal tuff in the upper part.
Definition of Lower Boundary: Conformably overlies the St Non's Sandstone Formation.
Definition of Upper Boundary: Passes upwards conformably by increase in grain size into the Caerbwdy Sandstone Formation.
Thickness: 15m
Geographical Limits: 1:50,000 Sheet 209 (St Davids) and adjacent Sheet 210, Pembrokeshire.
Parent Unit: Caerfai Group (CIS)
Previous Name(s): Cairfai Bay Shales Formation [Obsolete Name And Code: Use CFBS] (CABA)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Cliffs on west and east side of Caerfai Bay, 1.6km southeast of St David's, Pembrokeshire. Cowie, Rushton, and Stubblefield, 1972. 
Reference(s):
Rushton, A W A. 1974. The Cambrian of Wales and England, 43-121 in Holland, C H (editor), The Cambrian of the British Isles, Norden and Spitzbergen (Lower Palaeozoic rocks of the world, 2). [London: John Wiley and Son.] 
Harkness, R and Hicks, H. 1871. On the ancient rocks of the St David's promontary, South Wales, and their fossil contents. Quarterly Jounrnal of the Geological Society of London, Vol.27, 384-404. 
Thomas, H H and Jones, O T, 1912. On the Pre-Cambrian and Cambrian rocks of Brawdy, Haycastle and Brimaston, (Pembrokeshire). Quarterly Journal of the Geological Society of London, Vol.68, 374-401. 
Cox, A H, Green, J F N, Jones, O T, and Pringle, J. 1930. The Geology of the St David's district, Pembrokeshire. Proceedings of the Geologists' Association, Vol.41, 241-273. 
Cowie, J W, Rushton, A W A and Stubblefield, C J, 1972. A correlation of Cambrian rocks in the British Isles. Special Report of the Geological Society of London, No.2, p.26. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E209