How long have caves been there in their current form ?

[Ian P]

I’m quite surprised at the lack of knowledge on this subject by people who should know better.

Everyone knows Alum Pot was dug out by a Dragon who still lives down there. You quite often see the smoke from his breathing rising up.
The local farmers used to feed him with sheep to keep him content, however they realised that sheep cost money, but small children don’t…………

Happy to help on any other geological questions you may have !

 

[ChrisJC]

Maybe the glacial till which fell down the shaft was transported away by the massive meltwater flow entering from the more recently formed Long Churn system (and the even more recently formed Diccan Pot)?

I would have expected glacial till to have plugged the shaft, and not got washed away at all. That is if it went down there at all. Is there much of a thickness on the surface? I don't think there is is there?

Chris.

 

[MPC-Robin]

Thanks very much for all the information, most of it is way beyond what I understand so I will go with Ian P’s response that it was dug by a dragon. I suppose we were lucky not to see it on Sunday it must have been sleeping in Diccan somewhere. 😀

 

[Brains]

Think of the glacial action like coarse sandpaper and Alum as a crack in the wood. The valley bottom would be the work bench. The wood is abraded away (limestone pavement, U shape valleys, benches of limestone etc). The sawdust or moraine will fill the open crack, and settle in thick layers on the work bench. The crack may be emptied later, or may have filled with something else (ice) preventing it being filled. It may have only been exposed by the last rubs of the paper...
How's that for a mixed metaphor explanation?

 

[Andy Farrant]

Caves are often multiphase, having being formed over multiple glacial-interglacial cycles, so continue to develop through time. For example, GB has been actively forming for the past c. 1 million years, likewise, some of the older higher levels of Draenen are over 1.2 Ma, but the streamway is still active. Other caves may have only started forming at the end of the last glaciation (11,000 years ago); these are likely to be small and immature.

 

[Pitlamp]

Is there a definition of "immature" these days Andy? (Not trying to be pedantic; it's just that I got told off for using that word by "them as know".)

 

[Bob Mehew]

I think the limestone pavement common in the dales is the result of glacial removal of soils. This is backed up by the presence of erratic boulders. Such scraping would cause the overlying beds to be stripped away, leaving formerly closed avens as open shafts.

Jusdt come across some interesting work done by BritIce, see at Sheffield Uni and others, indicates moraines are visible around Alum Pot.

 

[garethjdavies]

I would guess, without any evidence, that it started forming about a million years ago, but would have accelerated as roof and wall collapse began along the fault zone as the water-table lowered and the 'support' of the water inside the cave drained. I've only been in Alum Pot once (prussicking up it), but it seemed like that's the way it would have formed. There is a description of the cave's formation in Volume 2 of Caves and Karst of the Yorkshire Dales, but not the age. Others better acquainted with the area than me will know more.

Recent data from the US have apparent Ice Age or Pleistocene development pushed back to well beyond 5.5 million years, Miocene or older. In what I have published I believe that the landscape today is very probably more than 7 million years old, that may approximate the age of some caves - generally as they appear today. Some began forming much much earlier - in east Tennessee there is a karst that is at least 60 million years old.