Rob said:
I have often thought it might be more interesting to know the depth relative to the surface directly above, in certain circumstances. And with modern digital mapping tools of the surface it is now getting much easier to actually calculate this.
This is similar to a question I posed a while ago, when I was looking for locations for testing cave radios; that is, where are the locations where the surface is the furthest away, in
any straight line. Obviously quite lot of supposedly "deep" caves could actually be quite shallow because, although they might sink high on a moor, they might terminate close to a resurgence. I didnt do any particularly serious or diligent research, but enough to produce a rough list of Dales caves in CREG journal 18 (December 1994).
The deepest in the Dales was, I guessed, a location in Dowbergill passage because, although the passage between Dow Cave and Providence Pot doesnt actually go very deep, Great Whernside rises above it, and so you can go 200m "deep" without actually descending very much.
If you avoid diving (and so you dont include Deep Well sump in GG at -195m, including -40m of dive) then the next deepest was, I thought, Meregill Hole, -172m at the bottom of the last pitch. But if you go along the Main Drain that takes you into a shallower zone because of the surface terrain.
All the other Dales locations I looked at were much shallower than 200m, and several did not actually involve much vertical caving. For example, Hall of Justice in the Sleepwalker series of White Scar Cave is up to 140m deep due to the surface terrain rising above it, and Valley Entrance in Kingsdale Master Cave is up to 90m deep as you walk in, under the hillside, to a location somewhere near the Master Junction.
Im told that North West Junction in Agen Allwedd is at -192m and that White Passage in Daren Cilau is at -198m, both of these allowing for the sloping surface terrain.
I would be interested to know of any other UK sites that are as deep, or deeper than these, especially if they are easy to get to