GeoGraph - photograph every grid square

Llyn Cau, Cadair Idris

Cadair Idris (893m) once thought to be an extinct volcano, and this lake now fills part of the crater. A lovely walk on a fine day. Photographed from the path due west of the lake.

The origin of corries is glacial. The rocks are of volcanic origin, but are often the results of ash flows from a distant mountain that has long since eroded away. A small glacier in a hollow eventually erodes out a bowl in the hillside, often with a water filled depression. Cwm Cau is a very fine example.