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“The site of the reported rockfall in GB near the waterfall climb in Main Chamber has been checked. There has been a recent fall of mud, gravel and smallish boulders on the left (when viewed facing downstream) of the waterfall climb, near the bottom. The wall above the last part of the climb (the big steps) appears as it did before, but should be considered loose due to the recent fall. The top part is calcited but might be subject to further falls, although it is equally possible that it might not change for a long time. However, as assessing such future possibilities is not an exact science, care should be taken here, and everyone should conduct their own risk assessments whenever they approach this area from any direction. There are still loose rocks almost covering the steps and when inspected it was not possible to pass the steps without using the unconsolidated debris. The floor below the climb is currently covered with unconsolidated debris and the boulders here will move underfoot when stepped on, so care should also be taken here.

This waterfall has been formed on a major vertical structural fault (see Ford, D.C., 1964. On the Geomorphic History of G.B. Cave, Charterhouse-on-Mendip, Somerset. UBSS Proceedings, 10(2) , pp 149-188 available from https://www.ubss.org.uk/resources/proceedings/vol10/UBSS_Proc_10_2_149-188.pdf), which states that there is much fault breccia to be found and so events of this nature are likely to occur from time to time.”

Graham Mullan
Secretary
Charterhouse Caving Company Ltd
secretary@charterhouse-caving-company.ltd.uk
8th Feb 2021

I have received a report of a substantial rockfall in G.B. I am told that

“In the region of 5-10 tons of sand, gravel and rock has slipped out of the left hand wall, just below the waterfall. There is a significant amount that has been undercut, but is still hanging high above the climb down. This appears to be very recent, given that the sand has not washed away yet and there was a pretty decent flow.”

Obviously nothing can be done to investigate and, possibly, stabilise this whilst we are under lockdown. It is recommended, therefore, that this area is avoided, including climbing the waterfall until a closer inspection can be made.

Graham Mullan
Secretary
Charterhouse Caving Company Ltd
secretary@charterhouse-caving-company.ltd.uk
2nd Feb 2021

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