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This is some additional information and pictures to support the geology walk from Porth yr Ogof to Sgwd Clungwyn, Ystradfellte, Powys. Take a look at the descriptions under each picture to see more information

The Localities mentioned on this post relate to the map which is included in the leaflet PDF and is repeated here to make this page easier to read. For more information and descriptions of all the localities and the start point, parking etc. please see the leaflet

To download and print this walk, please open / download the PDF version here

The Tradesman's Entrance to the Porth-yr-Ogof cave system at Locality 2. This leads to a dangerous part of the cave and should not be entered even under low water conditions !
Caving entrances to the Porth-yr-Ogof cave system on the way to Locality 3. These lead to deep shafts and are ddangerous. These should not be entered without the correct equipment and training!
The water at the Porth-yr-Ogof resurgence (Locality 4) may look inviting, but is deep, cold and dangerous and should not be entered!
Scwd Clungwyn at the viewpoint descrbed at the end of the description at Locality 5 The plane of the fault here is the line of the waterfall. you can see the water is at one side of the waterfall as described at Locality 6

A useful addition to your walk is the BGS Geology Viewer which is a free smartphone app to view geological maps of Britain wherever you go

We hope you enjoyed this short tour from Porth yr Ogof to Sgwd Clungwyn, Ystradfellte. If you’d like to learn more about our local geology, take a look at other pages on the South Wales Geologists’ Association website:

Saturday 7th January 2023: (Cardiff or Zoom)
Holiday Geology

Saturday 21st January: (Trallwn Community Centre, Swansea and Zoom)
Peter Kokelaar
Landscape evolution in southwest Wales: revelations of a dynamic Earth

Saturday 18th February: (Zoom Only)
Colin Palmer (IOW) – "The engineering of pterosaur flight" (provisional title)

Saturday 18th March: (Cardiff University and Zoom)
AGM and Peter Sheldon (Open University), "Exceptional fossils – the surprising, the significant and the strange"

You can view or download our newsletter here:

Oct 6 (Geodiversity Day)  - Duncan Hawley (HOGG),
"William Smith in South Wales" [Zoom (evening talk)]

Oct 29 - Professor Philip Hughes (University of Manchester), 
"Quaternary glaciation in the Mediterranean mountains - from Morocco to Montenegro" [Cardiff]

Nov 19 - Ewan Thomas (Geotechnology Ltd.),
"The work of an engineering geologist in South Wales" [Swansea]

Dec 10 - Professor Mike Searle, (University of Oxford)
"Tectonics and mountain building in the Himalaya" (provisional title)  [Zoom]

Jan 7 - Holiday Geology [Cardiff]

Jan 21 - Peter Kokelaar,
"Landscape evolution of southwest Wales: revelations of a dynamic Earth" [Swansea]

Feb 18 - Colin Palmer (IOW),
"Engineering research into pterosaur flight" (provisional title) [Zoom]

March 18 - Peter Sheldon (Open University),
"Exceptional fossils – the surprising, the significant and the strange’ [AGM Cardiff]