The steep sides of Nant Awen and its tributaries were mostly cut by the meltwater as the glaciers of the most recent ice age warmed up.
As the ice receded, vegetation, animals, and people weren't far behind.
And before the ice age? Read >here<.
The landscape is still continually changing - and at Ceibwr, you can help record the changes.
Nant Awen is marked on the map as Nant Ceibwr. But local wisdom is that the map makers weren't listening properly when they asked the name of the stream. Look at the names of the houses along its route: Aber-Awen, Glan-Awen, Blaen-Awen, Awen Fryn.