GeoGraph - photograph every grid square

The river bed of the Nant Dropyns or Afon Twymyn just downstream of Dylife (SN8694 : The Star Inn Dylife). The lead mining has left severe traces on the landscape: little vegetation can cope with the heavy metal concentration. I'm not clear about the name of the river at this point. My understanding was that it is called Nant Dropyns until it merges into the Nant Bryn-moel, which in turn becomes the Afon Twymyn downstream of the waterfall (SN8794 : Ffrwd Fawr) into the glacial Cwm Twymyn (SN8793 : Pen Cwm Twymyn). Fellow Geographer David Neal names this section, pictured from the opposite end (SN8693 : Former mine workings at Dylife), Afon Twymyn.