Wrong thread?
They do include a bit from Cresswell Crags which mentions witches' marks in the guff so I did ponder about putting it on Lankyman's Wild Flowers thread as they've been discussing rowan trees.
Ah, thanks, and apologies to the capn. I'd assumed that since it hasn't been broadcast yet nobody knew what was in it, and there's another thread that mentions witches, rowan trees, etc.
Was a bit short on area of coverage but I guess they have to be selective anyway and I suppose it would also depend on who sold the idea to the company. Beyond that it was general well done, the survey of Titan looked pretty impressive and the bit about the layer of volcanic stuff impacting on erosiveness was interesting.
I was looking at the scan and thinking 'the excavated bit comes in nowhere near the top'. The void seems to go up and almost reach the surface. Was there ever any chance of getting in right at the top and having an even bigger pitch?
Thanks, Mike. If I'm reading it correctly the original explorers followed a natural inlet in Titan ('the western passage') to a choke which was poked at, producing a slump in a shakehole on the surface. What I don't understand is why it took them years to excavate the current access route. Did they ignore this 'western passage' and mine a shaft and level through solid rock (which is what the film seems to suggest)?This explains why they dug where they did:
Titan Shaft
www.peakspeedwell.info
Reading Mike's link, poking the choke led to slumping at the surface, so the space between would be boulders, needing constant propping. If they'd been been mining through rock it wouldn't have needed rings. The film showed a big breaker but I assume that was to break boulders or for the passage in the film which looked mined. Having started from an estimated position at the surface and made the shaft vertical, maybe it didn't quite line up with the natural passage and they had to mine to intercept it?
Alas the bit about the layer of volcanic ash was pure bunkum. The production company just got in a well known TV presenter to add gravitas, but chose someone who knows nothing about caves. They didn't mention that Titan is one of the best examples of a phreatic vein cavity formed by deep-seated thermal water dissolving the limestone along mineral veins. The ash layer is just coincidental. Whilst they can form cave inception horizons, it does not explain the massive void that is Titan. Roo and Moose would have done a better job of explaining it. So a classic bit of telly where the focus is on entertainment rather than getting the facts straight. That said, I did enjoy watching it, I've seen plenty worse documentaries.
