Forest of Dean Coalfield

[1] The Forest of Dean Coalfield formed during Upper Carboniferous times, when the area was a nearshore-intertidal environment of semi-marine estuaries and swamps.

It occurs in a raised asymmetrical syncline with a steeper eastern limb that surfaces in the area of Staple Edge and the Soudley Valley producing the steeply dipping strata.

For much of their length, streams in the area run over impervious clay deposits, but, where valleys cut through the rim of the basin, carboniferous limestone and sandstone are exposed, allowing water to penetrate underground via swallow holes, cracks, and fissures.

In an attempt to reduce the pumping requirement, many mine owners 'waterproofed' the beds of watercourses with conduits or channels, wherever water loss was thought likely to occur.

[4] Towards the end of the 18th century, as the Industrial Revolution took hold, increasing demand for coal and iron led to conflicting mining interests and the court became bogged down with disputes.

Edward Terringham, a Gentleman of the Bedchamber in the court of Charles I was granted a monopoly to mine coal in the Forest, infringing the rights of freeminers and leading to widespread and sometimes violent confrontation.

[12] Initially, it proved impossible to produce coke from local coal that was ideal for smelting[13] which was a major factor in the failure of three early furnaces within a decade of them opening.

[14] The Coal Industry Nationalisation Act, of 1946 exempted the Forest of Dean, due to its unique form of ownership and history, allowing freemining privileges to continue intact.

[17] In 1904 some gales were amalgamated into seven groups in order to mine on a larger scale from deeper seams and the output reached one million tons annually.