New collieries, particularly in the western part of the coalfield where anthracite is found, were developed into the 1960s by the National Coal Board (for instance, Cynheidre Colliery No 1 shaft, at deep was sunk in 1954/6). Following the general collapse of the UK coal industry, most pits closed during the 1980s, with factors such as exhaustion of reserves and geological complexity adding to their problems. The last deep mine, at Tower Colliery on the north crop, ceased mining in January 2008. However, a few small licensed mines continue to work seams, mostly from outcrop, on the hillsides. Although some areas of the coalfield are effectively worked out, considerable reserves remain. However, the geological difficulties, which resulted in the closure of (for instance) Nantgarw colliery, make the cost of significant further extraction high. The coalfield experienced a late-stage development when opencast mining was commenced on a large scale, mostly on the gently-dipping north crop. In addition, old tips were reclaimed for their small coal content, which could be burned in power stations such as nearby Aberthaw. Most of the old sites have been filled and landscaped, but new operations continue.