Carboniferous Limestone

Carboniferous Limestone is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian Epoch of the Carboniferous Period. These rocks formed between 363 and 325 million years ago. Within England and Wales, the entire limestone succession, which includes subordinate mudstones and some thin sandstones, is known as the Carboniferous Limestone Supergroup.

Within Great Britain the suite of rocks known traditionally as the Carboniferous Limestone Series was deposited as marine sediments in three distinct ‘provinces’ separated by contemporary landmasses. One of these landmasses was the Wales-London-Brabant Massif, an east-west aligned belt of land stretching through central Wales and the English Midlands to East Anglia and on into Belgium. The limestones deposited to its south form a distinct South Wales-Mendip province which extends from Pembrokeshire in the west through southern Carmarthenshire, Glamorgan and south Powys to Monmouthshire, Gloucestershire and north Somerset. These rocks continue eastwards at depth beneath Oxfordshire. The Carboniferous Limestone sequence of South Wales and the Bristol area is currently (2012) subdivided thus:

The limestone found north of the Wales-London-Brabant Massif and south of the emergent Southern Uplands block is identified as a separate northern province. It is characterised by the presence of numerous ‘blocks’ and ‘basins’ each with its own particular depositional style.

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