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Geological Walk at Penwyllt and Ogof Ffynnon Ddu

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This is some additional information and pictures to support the geology walk at Penwyllt and the ogof Ffynnon Ddu nature reserve. 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

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If you take the optional walk down the hill (and back), down through a wooden gate you can find the Ogof Ffynnon Ddu resurgence which is Locality 2. Resurgence is the term that describes the point at which an underground river reappears at the surface as as spring, the water here has flowed through the cave system and is cold even at the height of summer
South is to the right of this picture of the quarry face at Locality 3 The limestone dips in this direction.
Overview of the crags at Locality 4
The chert in the limestone at Locality 6
The wall of Penwyllt Bricks at the old Brickyard (Locality 7) should not be disturned or climbed on
At the old brick Kilns at Locality 7 you can find the glassy surfaces where the inside of the kilns melted

Below is a slideshow of pictures of the cave passages inside the "Top Entrance" of the cave seen at Locality 8

Click on the images to se elarger versions or manually drive the slideshow or just let it run

The view across the valley from Locality 10 to Fan Hir with the glacial morraines at the foot of the escarpment

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 https://www.bgs.ac.uk/technologies/apps/igeology-app/

We hope you enjoyed this short tour of Penwyllt and Ogof Ffynnon Ddu. If you’d like to learn more about our local geology, take a look at other pages on the South Wales Geologists’ Association website: www.swga.org.uk