Carboniferous, introduction, Wales

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From: Howells, M F. 2007. British regional geology: Wales. Keyworth, Nottingham: British Geological Survey.

Dinantian palaeogeography (adapted from Freshney and Taylor 1980). P916180.

Recent palaeomagnetic and structural studies in the Upper Palaeozoic rocks across Europe have indicated that the Carboniferous sequences in the British Isles accumulated to the north, on current coordinates, of a micro-plate collision zone that lay across central Europe, between Armorica, the Massif Central and the Vosges. On the north side of this zone, the Rheno-Hercynian Basin, floored by ocean crust, was systematically closed by northward-directed thrusting that persisted into late Carboniferous times. Farther to the ‘north’, the British Isles lay on a foreland where, in response to tectonism, a series of faulted basins developed on either side of a landmass, which has been referred to as St George’s Land but is now included in the Wales–Brabant massif (P916180). The basins and adjacent platforms became the controlling influence in Carboniferous sedimentation.

The Carboniferous sequence includes a range of shallow marine carbonates, fluviodeltaic and shallow marine siliclastic deposits, lacustrine sediments and coal. The distribution of facies indicates a continuous interaction between terrestrial and marine influences, and the temporal variations reflect both climatic and sea level changes. One of the most discussed features of the sequence is the cyclical patterns that have been variously ascribed to eustatic, tectonic and autocyclic sedimentary mechanisms; all these mechanisms were probably operative.

Biostratigraphical schemes based on microfloras, conodonts and foraminifera complement the long established stratigraphy based on the macrofaunas. The three main lithostratigraphical divisions of Carboniferous Limestone, Millstone Grit and Coal Measures have been recognised since the early 19th century, and have been related to the chronostratigraphical divisions, Dinantian (Tournaisian and Visean), Namurian and Westphalian. The sequence includes the coal, ironstone, clay and limestone, which have been so intensively exploited, making this the most economically important part of the stratigraphical sequence in Wales.


BARCLAY, W J. 1989. Geology of the South Wales Coalfield, Part II, the country around Abergavenny. Third edition. Memoir of the British Geological Survey. Sheet 232 (England and Wales).

DINELEY, D L. 1992. Devonian. 179–205 in Geology of England and Wales. DUFF, P MCL D, and SMITH, A J (editors). (London: The Geological Society of London.)

FRESHNEY, E C, and TAYLOR, E A. 1980. The Variscides of south-west Britain. 49–57 in United Kingdom introduction to general geology and guides to excursions. OWEN, T R (editor). Proceedings of the 26th International Congress, Paris, 1980.

GAYER, R, FOWLER, R, and DAVIES, G. 1997. Coal rank variations with depth related to major thrust detachments in the south Wales coalfield: implications for fluid flow and mineralization. 161–178 in European coal geology and technology. GAYER, R, and PES EK, J (editors). Geological Society Special Publication, No. 125.

GEORGE, T N. 1970. British regional geology: south Wales. Third edition. (London: HMSO.)

HAMPSON, G J, ELLIOTT, T, and DAVIES, S. 1997. The application of sequence stratigraphy to Upper Carboniferous fluvio-deltaic strata of the onshore UK and Ireland: implications for the southern North Sea. Journal of the Geological Society of London, Vol. 154, 719–733.

JONES, D G. 1074. The Namurian series in south Wales. 117–132 in The Upper Palaeozoic and post-Palaeozoic rocks of Wales. OWEN, T R (editor). (Cardiff : University of Wales Press.)

KELLING, G. 1974. Upper Carboniferous sedimentation in South Wales. 185–224 in The Upper Palaeozoic and post-Palaeozoic rocks of Wales. OWEN, T R (editor). (Cardiff: University of Wales Press.)

POWELL, C M. 1989. Structural controls on Palaeozoic basin evolution and inversion in south-west Wales. Journal of the Geological Society of London, Vol. 140, 439–446.

RAMSBOTTOM, W H C. 1973. Transgressions and regressions in the Dinantian: a new synthesis of British Dinantian stratigraphy. Proceedings of Yorkshire Geological Society, Vol. 39, 567–607.

THOMAS, L P. 1974. The Westphalian (Coal Measures) in south Wales. 133–160 in The Upper Palaeozoic and post-Palaeozoic rocks of Wales. OWEN, T R (editor). (Cardiff: University of Wales Press.)

WARREN, P T, PRICE, D, NUTT, M J C, and SMITH, E G. 1984. Geology of the country around Rhyl and Denbigh. Memoir of the British Geological Survey, Sheet 107 and parts of sheets 94 and 106 (England and Wales).

WATERS, C N, BROWNE, M A E, DEAN, M T, and POWELL, J H. 2007. Lithostratigraphical framework for Carboniferous successions of Great Britain (onshore). British Geological Survey Research Report, RR/07/01.

WHITE, S. 1991. Palaeogeothermal profiling across the South Wales Coalfield. Proceedings of the Ussher Society, Vol. 7, 368–374.

WILSON, D, DAVIES, J R, FLETCHER, C N J, and SMITH, M. 1990. Geology of the south Wales Coalfield, Part VI, the country around Bridgend. Second edition. Memoir of the British Geological Survey, Sheets 261 and 262 (England and Wales).

WOODLAND, A W, and EVANS, W B. 1964. The geology of the south Wales Coalfield. Part IV. The country around Pontypridd and Maesteg. Memoir of the Geological Survey of Great Britain, Sheet 248 (England and Wales).

WRIGHT, V P. 1996. Use of palaeosols in sequence stratigraphy of peritidal carbonates. 63–74 in Sequence stratigraphy in British geology. HESSELBO, S P, and PARKINSON, D N (editors). Geological Society of London Special Publication, No. 103.