Pwll Mawr Colliery was sunk in circa 1772 by John Smith, on the site of a borehole made by Chauncey Townsend circa 1770. It worked the Great or Six Foot Seam. The shaft was 137 metres deep and was worked until 1828 when a disastrous explosion led to its closure. In 1872 it was aquired by Evan Mathew Richards and re-opened in 1881. The rusticated pump-bob wall remains of the engine-house date from this period. They are located on on the open-ground to the east of the main railway-line leading into Swansea from the north-east. Being the first shaft to reach the Swansea Six Foot Seam in 1770, the present ruin is of considerable historical significance. The mine finally closed circa 1893.
Sources:
A Guide to the Industrial Archaeology of Swansea Region, by Stephen Hughes and Paul Reynolds, AIA, 1989
Site entry by Stephen Hughes for Buildings of Glamorgan, John Newman, 1995
