Maerdy Collieries No.3 Pit was sunk in 1893 near the head of Cwm Rhondda-fach some 1.5km to the north west of Nos.1 and 2 Pits (nprn 80554); No.4 Pit was sunk in 1914 some 85m to the south of No.3. Closed in 1940, the mine was abandoned and lay derelict. The coal industry was nationalised in 1947 and two years later the National Coal Board announced the complete rebuilding of the mine (see nprn 33505) which swept away most traces of the original structures.
B.A.Malaws, RCAHMW, 20 January 2009.