August 21st, 2007

Met Rex at the mountain centre in Libanus this morning and assisted him with running a geologically themed walk around the area. The walk was ten miles long and we had three people on the walk with us.

The walk took us first to Twyn y Gaer - a hillfort to the North east of the mountain centre. Here is some information from the National Park website on the hillfort:

This hillfort lies about 5km west of Brecon at the northern end of a strip of common land owned by Brecon Beacons National Park Authority. There is open access to the site. A public right of way (Heol Cefn-y-gaer) runs north-south past the site. The hill which rises to a height of 367m is composed of mudstones and siltstones of the St Maughan’s Formation which include two or three bands of sandstone.  Ripple marks can be seen in the quarried slabs of the uppermost band near the trig point which crowns the hill. Of rather later origin are a series of ‘pillow mounds’ on the southern and eastern flanks of the hill.  These low mounds were provided in connection with the breeding of rabbits in recent centuries. 

From here we went on to a disused quarry near Allt Lom where there is evidence in the rock of a fossilised riverbed. 

We then walked a short section of Sarn Helen - the roman road - before heading for Cefn Llechid (400m) where we had lunch and took in the stunning panoramic views. We then followed the bridleway south down from Cefn Llechid and onto the road for a short period. On the way back we passed the fens and raised bogs of Traeth Mawr - which is designated as a SSSI (Site of Special Scientific Interest). For more information follow this link: http://www.breconbeacons.org/content/environment/bd-in-the-bbnp/wetlands-and-open-water/raised-bog 

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