Cwl Teigl is a small C19 slate quarry (nprn 537493) marked as disused on the 1891 OS map. The dam was the reservoir for the quarry waterwheel. It is a drystone wall oriented NNE-SSW, partly faced with slabs. It is 16m long, 1m thick and up to 1.6m high, but partly collapsed. It dams a swampy depression, 50m N-S x 40m, perhaps a natural lake. Water was conveyed to the quarry by a leat (NPRN536810).
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H & H, 15/01/2014.