The glistening chunk of coal in the photo is a sample of the Warwickshire Thick Coal, collected from the former Daw Mill Colliery near Arley. It is on display at the Market Hall Museum in Warwick. Daw Mill was Warwickshire’s last deep coal mine, and was finally closed in 2013, following a fire. At the time of its closure, this mine was Britain’s biggest coal producer and employed 650 people. Daw Mill was a large-scale and complex operation, involving shafts sunk to depths of more than 500 metres to extract the Thick Coal.
National significance, and decline
Going further back to the late 1940s, the Warwickshire Coalfield as a whole was a major national coal producer, with nearly 20 recorded collieries working a number of different seams. All except Daw Mill had gone by the early 1990s.
An earlier history
At Daw Mill the Warwickshire Thick seam, lying hundreds of metres underground, was up to around eight metres thick. It formed through the natural amalgamation of several thinner seams, separated elsewhere by seams of clay or sandstone. Like most other British coals it originally formed as a build-up of peat deposits in an area of equatorial rain forest swamps and bogs, roughly 300 million years ago.
The present informs the past
Today, the ancient swamps and their sedimentary deposits make up the so-called Coal Measures rock beds of the Warwickshire Coalfield. Further afield in Britain, the distribution, geological make-up and fossil discoveries of our other coalfields allow us to reconstruct this lost world, and its extinct plant and animal inhabitants.