These spoil tips are a fine example of terraced heaps of large slate waste, tipped in parallel rows on the north-east flank of Cwmorthin. The five levels correspond with Levels 3 to 7 of the underground workings, from which tramways at each level carried the waste blocks for tipping. The tramways once crossed the main quarry incline (NPRN 408415) on bridges, but these features and the terraces to the north-west have been destroyed in recent years by reworking of the tips.
W J Crompton, RCAHMW, 12 November 2008.