Guided Walk with Alan Bowring
On a beautiful warm afternoon 12 keen members drove across the new Gateway Bridge over the Clydach Gorge to the escarpment near Pant-y-Rhiw high above Llangattock and Crickhowell.
We were met by Alan Bowring (The Forest Fawr Geopark Development Officer) and his colleague Keira who proceeded to take us on an extended tour of the cliffs in the area.
The main site is known as Craig y Cilau. The obvious feature which can be seen from a great distance is a line of cliffs which have been extensively quarried in the nineteenth and early twentieth centuries. Access to the area for extraction of limestone wa provided by a tramway in the direction of Blaenavon and by an incline and tramway to the Mon. & Brecon canal at Llangattock. The stone was used to provide lime from kilns for construction and agriculture and as a flux in the iron industry.
The extensive quarrying has revealed the layer of rock which make up the hillside and Alan was able to explain the formation of the layers above overlying Old Red Sandstone at the base. The limestone is banded with layers of conglomerate and sandstone. From above the rock comprises Carboniferous Coal Measures, Trwch Limestone, Dowlais Limestone, Llanelly Formation and Abercrinan Oolite. it was noted that some of the horizontal bands have been Dolomitised which renders them useless for industry so that they were discarded as quarrying proceeded.

We visited old lime kilns and then walked along the base of the cliffs to view the remains of the working. Among the detritus there were fascinating boulders of banded rock with some interesting curved fossilised trails of worm like creatures in the mudstone. Lichens formed some strange and wonderful patterns on the fallen rocks. We also saw an impressive area of flowstone cascading down a cliff.
The entrance to the extensive caves which lie in the hillside was viewed.

The extent of the quarrying is most impressive and explains the large amount of spoil which hs been left behind.
Towards the west the escarpment has not been quarried and Alan led a group discussion about the origins of the formation of the giant cirque in the cliffs. The exact formative forces are not universally agreed. There was almost certainly glacial activity but an early meander of the River Usk could also have had a major impact on the existing shape of the land.

We were shown examples of rare whitebeam which is only found on these cliffs.
We returned to the carpark by the old tramway and were able to see the top of the incline and to see examples of the flat stones and shaped cast iron brackets which used to carry the iron tramlines. We passed the HQ of the Chelsea Caving Club which despite its name, is now the local club for speleologists.

Alan kept us enthralled for more than 3 hours by his knowledge of not only geology but also many wider aspects of the National Park and its flora and fauna.
Many thanks to him, his assistant and of course Jim Handley who arranged it all.
Martin