OFD at Penwyllt, near Abercrave in South Wales, is one of the UK's major cave systems. It's name Ogof Ffynnon Ddu means 'Cave of the Black Spring’ and was first discovered in 1946.
Above is caver James Thorn in Selenite Way, OFD.
Cave formations are called speleothems although often known as 'pretties' by cavers. The creation, type and colouration of pretties depends upon the amount of surface water entering the cave, minerals dissolved in the water, the type of rocks in and around the cave and the cave environment such as air flow through the cave, humidity and temperature.
Just click on any picture to see it larger.....
Please note these photographs are copyright Annette Price and cannot be used without permission.
Below is a selection of cave pretties, mostly stalactites hanging down from the cave roof
The above stalactite is known as a 'straw' as it is the same width as a drinking straw and hollow. The water drop at the end of this straw, is about to fall having traveled through the straw rather than over it. Straws are formed from drops of water containing dissolved minerals; calcium carbonate and calcite dripping from the cave roof, leaving behind a minute deposit in the shape of a ring. Over time, more minerals are deposited on the ring and gradually a hollow tube forms hanging from the ceiling. Typically straw formation takes around a hundred and fifty years per inch. Straws are incredibly delicate and fragile, great care is needed while moving around the cave and photographing them to not touch or break them.
Here we see typical 'Cave Life' to be found in OFD cave. These cavers are from Croydon Caving Club, of which I am also a member. www.croydoncavingclub.org.uk
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