The BGS Lexicon of Named Rock Units — Result Details

Cwrt-yr-ala Formation

Computer Code: CWA Preferred Map Code: notEntered
Status Code: Full
Age range: Late Devonian Epoch (DU) — Late Devonian Epoch (DU)
Lithological Description: Thinly interbedded quartzitic sandstones, siltstones and mudstones with subordinate thick commonly pebbly sandstone units; nodular calcretes well developed; the lithologies arranged in fining-upwards cycles.
Definition of Lower Boundary: At the unconformable junction with the drab brown to purple sandstones of the Brownstones Formation, at 182.72 m in the Cwrt-yr-ala Borehole.
Definition of Upper Boundary: At the sharp junction and appearance of multi-storey sandstones with beds of quartz-conglomerate of the Quartz Conglomerate Group, at 99 m in the Cwrt-yr-ala Borehole.
Thickness: 15 m to 73 m.
Geographical Limits: Both limbs of the Cardiff - Cowbridge Anticline and in small inliers to the south at Cyntwell and Cwrt-yr-ala.
Parent Unit: Portishead Subgroup (POB)
Previous Name(s): Quartz Conglomerate Group (South Wales) (QCG)
Quartz Conglomerate Group (South Wales) (QCG)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  IGS Cwrt-yr-ala Borehole, Cardiff, South Wales [ST 1403 7339], Waters and Lawrence (1987). 
Reference(s):
Waters, R A and Lawrence, D J D. 1987. Geology of the South Wales Coalfield - Part III: the country around Cardiff. Memoir of the British Geological Survey, Sheet 263. (England and Wales). 
Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E263 E262