The geography of the lower Afan Valley is delineated primarily by the surrounding mountains, with Mynydd Foel (y Foel) dominating the West side of the lower valley, Mynydd Dinas to the East, and Afon Afan (the River Afan) that flows along its length.
The village of Cwmafan sits on the valley floor, on the banks of the River Afan. The adjunct communities of Brynbryddan and The Graig sit on the side of y Foel. Travelling South in the lower valley leads through the small village of Pantdu and to the town of Aberafan (aka Port Talbot). At the North end of the lower Afan Valley, past Pwllyglaw, are the communities of Pontrhydyfen and Oakwood.
From Pontrhydyfen, the B4287 road leads to the villages of Efail Fach and Tonmawr, and via the village of Cimla to the town of Neath (Castell Nedd) in the Neath Valley.
Over the hill from the A4107 at Ynysygwas is the small village of Bryn, en route to Maesteg. According to Wikipedia, the original name was Bryntroedygam, and the 1876 Ordnance Survey map shows a farm by the name Bryn-Troed-y-Garn.
The upper Afan Valley is a narrow valley with heavily wooded steep sides, dotted with a number of villages that were home to coal miners and their families. Villages in the upper valley include Cynonville, Dyffryn, Cymer, Abercregan, Glyncorwg, Croeserw, Abergwynfi and Blaengwynfi.
Over the hill from Cymmer is the community of Croeserw. For some years, the community was also called by the unflattering nickname given to the local pub: Croeserw Hotel = The Bog. I don’t know the origin of the nickname. In 2004 Wales Online stated that the community had the title of the sickest community in England and Wales, with more than 40% of its adults crippled by a long-term limiting illness.
Continuing on the A4107 from Abergwynfi over the mountain known as y Bwlch brings you to Treorci (Trehorcy) in the Rhondda Valley.
Elevation/altitude of the lower valley floor is approximately 110 feet above sea level, and y Foel rises to approximately 1,200 feet.