Excursion Report - The Castleton Area

July 13th 2008

On a perfect day ten members met Professor Gerry Slavin in the long term car park at the Speedwell Mines. He introduced himself by saying that he was, formerly, a pathologist and was and is a keen amateur geologist. We set off towards the Speedwell Cavern entrance and turned off just before Winnats Pass. Gerry explained that we were now at the junction of the fore reef and basinal deposits. We found pebble like fossil brachiopods and the area had in the past been considered as a beach, however the sequence of grading suggests turbidites, the material being washed from the shelf in catastrophic events. We then walked below Long Cliff and observed old workings and the washouts from ‘wush’ mining techniques. Evidence of volcanism was found in the basalt with its weathered ‘rind’ thought to be an intrusive feature.

We walked on to the Peak Cavern (aka the Devil’s Xxxx), some 10m high and 30m wide. The three large chambers, the Vestibule, the Great Cave and Roger Rain’s House, were all formed by solution along the bedding planes in lenticular backreef shoals, which eventually led to joint block collapse.

It was then time to examine Russett Well (by kind permission of Mr Peter Harrison) in which the drainage of the Peak Cavern emerges at depth and flows away into the village of Castleton. This prompted a discussion about percolating water and allochthonous water and the dye experiments which had mapped out the course of various bodies of water.

Next came Cave Dale, which is entered through a gorge which cuts through the fore reef, into the muddy micritic ‘reef’ and thence through to the bedded Bee Low Limestones, which are internal to the reef. As we walked up the reef, drainage became an issue once again with water appearing and disappearing as it percolated through the joints into Roger Rain’s House and onto the paying customers! Beyond the reef volcanism is again in evidence with columnar joining of basalt extending some 150m along the Dale. Further along the Dale widens and cuts through thick well bedded limestone.

(Left) The Castleton group: Liz Bellamy, John Ingall, Ron Johnson, Gerry Slavin, John Hudson, Dennis Gamble, Helen Jones, Graham Cheesman, Dorothy Sowerby, Albert Benghiat, Joe Sowerby (photo: Joe Sowerby)

We enjoyed our lunch looking towards Hurdlow. The top of Hurdlow is marked by spoil as cavers improve the access to Titan cave. Unfortunately the cavers were absent but Ron Johnson was able to explain how cavers overcome restricted access to explore cave systems.

After lunch we visited Dirtlow Pit/Rake, which has been infilled, but it was still possible to observe the avenas from the rim. These are possibly formed by the rush of underground streams sending water spiralling upwards and exploiting lines of weakness to create cone shaped voids with ridged sides. We then walked back towards Castleton, stopping en route to rummage over spoil heaps for mineral specimens, which included flowstones, barite, fluorite, calcite, galena and limestones containing bitumen (oil crisis, what oil crisis!). Finally we walked past the workings of Hope Quarry and enjoyed fine views of the basinal Edale Shales.

A good day was had by all, although, at times, Gerry’s definitions of ascent and descent were questioned! Field Secretary Helen Jones proposed the vote of thanks and the meeting ended at 4pm.

Helen Jones

This item was published in the Autumn 2008 issue of 'Charnia' Newsletter