Cavematt
Well-known member
Up in the North York Moors, we have been treated to some great discoveries over the last decade, including a 1km+ extension to Jenga/Excalibur Pot in 2020.
However, all open and obvious leads in Jenga/Excalibur are now exhausted (except for the four sumps which await divers and are sure to add hundreds of metres more passage and possibly the fabled link to the River Dove or Bogg Hall). Also, accessing the Jenga extensions is not viable October to April due to flooding. Hence we have been on the lockout for our next project.
Should we return to some of our more speculative, uninspiring digs? Manor Vale? Mutton Butty? Glass Trap? Enthusiasm was not high for any of these.
Thankfully, last summer, a new project came to light at a site we have been interested in for some time, where a change in land ownership has now enabled consented access for a dig. This site is near to the village of Cropton, 4-5km east of the Jenga/Excalibur system, at the top end of the limestone.
Here, a small stream (which only flows when the ground is saturated) disappears into the ground at the top end of the Jurassic limestone, at the end of a usually dry valley, with about 3-4km horizontal range and 50-60m vertical range to where most of the regions resurgences are found.
Progress was slow, as getting down through several metres of upper non-limestone rock was challenging. Thankfully the really friendly landowner was on hand with a JCB to expedite this, getting us down 4m into a small, dry cave passage leading off into darkness.
This passage was not straightforward. We were not properly into the top of the limestone yet, so the roof had flaked large slabs across the passage where it has collapsed in multiple places, and progress through Autumn and Winter has involved pushing along the passage, removing boulder obstacles. At times it has felt like an underground boulder labyrinth, but in fact we are following a large passage, just one full of blocks. Progress has sometimes been only 1m per week!
The draught is excellent here, and the prospect of sinking water nearby kept us going.
It was at some point in November that the first heavy rain of winter happened and the sinking stream (The Shite Brook) suddenly entered the cave about 10m along the passage, bringing with it some foul smells for the first week of flow until it flushed through whatever the offending matter was.
The stream flowed off tantalisingly through boulders, accompanied by the ever-present-draught.
More boulder mining identified that we had now achieved a solid, water-worn roof, and solid cave walls in a passage 2m wide by 1.5m tall. The challenge was a number of large slabs that continued to block the way. In the sessions just before and during Christmas more blocks were cleared, and ahead, the most enticing black voids yet appeared, with the sound of the stream gurgling into the distance.
On 4th January, after a few more hours of boulder removal, we got a mini breakthrough and crawled forward 10m just above the stream and into a 5m long, 2m wide chamber with a few formations. At the end of the chamber is a way on, flat out in the stream and going off several metres, with no end in sight. This is our target for this week, although some dodgy blocks need to be stabilised first and the stream may need some dredging of cobbles.
We are now about 30-40m into the cave in total. The further in we get, the more water-worn it becomes, the more cave-like and phreatic it appears, and the more space we are getting between obstructing blocks (although we are far from clear of these). Plus, there is a stream vanishing into the cave and a strong draught either howling in or out (typically out, but last week it was strongly drawing in).
What we do have here for sure is the second, explorable, active stream cave in the North York Moors, if you count the entire Excalibur/Jenga/Bogg Hall/River Dove as one cave system.
Excitement is mega-high for the coming weeks. Will we get through the boulders and into glorious stream passage heading off down the valley? Will this become the second North York Moors mega-system? Or is this going to become a several year mining project through hundreds of metres of block-choked streamway? Is it going to spontaneously close down to an impenetrable wet bedding? Time will tell, but we are feeling fairly upbeat right now.
In the meantime, we have put together the following video from the session last week with the mini-breakthrough and open (albeit small) passage ahead. Enjoy…
However, all open and obvious leads in Jenga/Excalibur are now exhausted (except for the four sumps which await divers and are sure to add hundreds of metres more passage and possibly the fabled link to the River Dove or Bogg Hall). Also, accessing the Jenga extensions is not viable October to April due to flooding. Hence we have been on the lockout for our next project.
Should we return to some of our more speculative, uninspiring digs? Manor Vale? Mutton Butty? Glass Trap? Enthusiasm was not high for any of these.
Thankfully, last summer, a new project came to light at a site we have been interested in for some time, where a change in land ownership has now enabled consented access for a dig. This site is near to the village of Cropton, 4-5km east of the Jenga/Excalibur system, at the top end of the limestone.
Here, a small stream (which only flows when the ground is saturated) disappears into the ground at the top end of the Jurassic limestone, at the end of a usually dry valley, with about 3-4km horizontal range and 50-60m vertical range to where most of the regions resurgences are found.
Progress was slow, as getting down through several metres of upper non-limestone rock was challenging. Thankfully the really friendly landowner was on hand with a JCB to expedite this, getting us down 4m into a small, dry cave passage leading off into darkness.
This passage was not straightforward. We were not properly into the top of the limestone yet, so the roof had flaked large slabs across the passage where it has collapsed in multiple places, and progress through Autumn and Winter has involved pushing along the passage, removing boulder obstacles. At times it has felt like an underground boulder labyrinth, but in fact we are following a large passage, just one full of blocks. Progress has sometimes been only 1m per week!
The draught is excellent here, and the prospect of sinking water nearby kept us going.
It was at some point in November that the first heavy rain of winter happened and the sinking stream (The Shite Brook) suddenly entered the cave about 10m along the passage, bringing with it some foul smells for the first week of flow until it flushed through whatever the offending matter was.
The stream flowed off tantalisingly through boulders, accompanied by the ever-present-draught.
More boulder mining identified that we had now achieved a solid, water-worn roof, and solid cave walls in a passage 2m wide by 1.5m tall. The challenge was a number of large slabs that continued to block the way. In the sessions just before and during Christmas more blocks were cleared, and ahead, the most enticing black voids yet appeared, with the sound of the stream gurgling into the distance.
On 4th January, after a few more hours of boulder removal, we got a mini breakthrough and crawled forward 10m just above the stream and into a 5m long, 2m wide chamber with a few formations. At the end of the chamber is a way on, flat out in the stream and going off several metres, with no end in sight. This is our target for this week, although some dodgy blocks need to be stabilised first and the stream may need some dredging of cobbles.
We are now about 30-40m into the cave in total. The further in we get, the more water-worn it becomes, the more cave-like and phreatic it appears, and the more space we are getting between obstructing blocks (although we are far from clear of these). Plus, there is a stream vanishing into the cave and a strong draught either howling in or out (typically out, but last week it was strongly drawing in).
What we do have here for sure is the second, explorable, active stream cave in the North York Moors, if you count the entire Excalibur/Jenga/Bogg Hall/River Dove as one cave system.
Excitement is mega-high for the coming weeks. Will we get through the boulders and into glorious stream passage heading off down the valley? Will this become the second North York Moors mega-system? Or is this going to become a several year mining project through hundreds of metres of block-choked streamway? Is it going to spontaneously close down to an impenetrable wet bedding? Time will tell, but we are feeling fairly upbeat right now.
In the meantime, we have put together the following video from the session last week with the mini-breakthrough and open (albeit small) passage ahead. Enjoy…
thanks
