The BGS Lexicon of Named Rock Units — Result Details
Cwrt-yr-ala Formation
Computer Code: | CWA | Preferred Map Code: | notEntered |
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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) |
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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 |