Lewis Morris' early chart for Goldtop Road and St Bride's Bay notes a coal works to the north of Little Haven. OS 1st edition mapping shows a 'Old Culm Pits' in an area of waste ground with a large pool or lake with marsh at its edges. The lake measures some 240 x 45m and is still shown (much smaller) on modern OS mapping.
Sources include:
Morris, L, 1748, Plans of Harbours, Bars, Bays and Roads in St George's Channel, plate 22
OS 1st edition 25in