Digging in the approach passage to North Choke.
The Shaft at Cannington was found by somebody examining baryte veins and entered in The Mendip Cave Registry as Castle Hill Quarry Shaft last year.
This long view shows the entrance just behind the middle digger.
The depth to the local water table is an estimate as a steep and very loose boulder slope drops into a roomy chamber. Boulders rolled down this go around a corner and make a long drop with a booming sound into deep water. It would need a lot of work in full view of the quarry offices to make this safe. At the moment the lower benches are being removed with a 15m zone left intact at the entrance. The quarry will move away from here to a new extension at the quarry entrance ( As per planning application posted on line ).
Castle Hill as seen from the seaward side. Extraction is curtailed by an ancient hill fort on the high point.
The earlier, very large, chamber known as Jackdaw Cave would have been near the centre some 200m East of the shaft. The history of that appeared in Descent.
Clearly Castle Hill Quarry Shaft is important from a geological point of view having formed in a baryte vein and ending in deep water with the possibility of further large chambers similiar to Jackdaw Cave. The original explorers of Jackdaw Cave found an intact aurochs skull ( now in Bridgwater museum )and a large talus cone was never properly investigated.
Still you have to tread carefully with quarry owners. My wife's cousin manages one near Bristol airport. I asked him if they ever found any caves or shafts. He said that they did and were filled in imediately for H and S reasons. I asked if I could look at any new ones and he said not bloody likely so there you are.
Castle Hill Quarry Co don't encourage visitors either.
There are cameras as people pinching diesel and causing damage have been a problem. We shall have to wait for an invitation.