tim.rose2
Active member
A new dig, well actually a very old one revisited...
North Passage in Sandy Hole is essentially the continuation of the entrance phreatic tunnel beyond the inkwell. This would have been an isolated phreatic running approx. 4 ft above the main North-South Passages in the cave had the bottom not fallen out of it where it intersects Gold & Silver Passage to create a junction. To demonstrate the point, only a few metres further ahead, North Passage passes directly over Paul's Progress. The vertical distance between the two can only be few inches, yet when in either passage you are blissfully unaware of the others existence. Until yesterday, North Passage ended at a calcited choke where it had been intersected by a much younger mass movement rift 26 m North East of the Inkwell, heading inland (shown on the survey below). 12 m North of North Passage is another small phreatic (Shitzentrasse) heading in a similar direction also ending choked at a rift on a similar longitude - presumably the same rift.
North Passage is an arduous flat out crawl varying from 3 to 5 ft wide, ending very cramped with little to no stacking space along it's entire length. The terminal choke consists of calcited infill. The Hardye's School CCF briefly had a go at digging this in the early 1970's not long after its discovery but made little progress due to the cramped conditions and loosing interest upon discovery of Ariel cave in 1974. Inevitably the choke would only be the width of the rift (approx. 2 ft), however as this is near the bottom of the limestone and the rift probably extends 20m above - like a good game of kerplunk, remove the wrong stone and there's a good chance of bringing down a lot of debris, making it a very long 2ft! To my knowledge, nobody has tried to dig North Passage since the 1970's and I dare say few have visited either.
The interest is fairly obvious - a downstream water worn passage, heading inland into an area beyond all known passages. The water obviously went somewhere and there's zero chance of that being a resurgence without crossing the entire island. Furthermore the existence of Shitzentrasse a few metres North gives hope the two passage will unite, as is seen at the confluence in Ariel Cave, resulting in an enlargement. Extrapolating further, wouldn't be it nice it they flowed into another (larger) inland North - South passage! This is very much one of those places that had it have been in a major caving region would have been pushed to a conclusion decades ago.
Sunday 5th Jan, myself and Dan set off to the end of North Passage to determine if there's any hope of passing the choke. Several knackering hours of mostly hammer and chisel work in an extremely constricted space, and at the point of more or less exhausting the limited places we had to loose spoil, we managed to open a small hole through the choke providing a view of the continuing passage. We were both too knackered to do anything about it so it had to wait until yesterday. Saturday 11th Jan - Mike K kindly agree to a trip to push the end with me on the promise of a certain breakthrough... It took Mike about 20 mins to enlarge the hole through the choke to a size we could pass but he was met on the far side with an extremely frustrating passage... Not quite big enough. The phreatic was approx. 18 inches high, 4 to 5 ft wide (sounds good) but with a 6 inch layer of extremely sticky mud in the floor and occasional rocks from either ceiling collapse or that had dropped down narrow rifts making easy progress impossible. If the passage was 6 inches higher or the mud not present we've have simply crawled ahead. Instead Mike spent the next 3 hours channelling a route through by pushing mud and rocks side ways whilst I followed behind further enlarging and improving the stacking to maximise space. We reckon we've more of less doubled the length of North Passage in doing this, perhaps adding around 20 m beyond the end shown in the survey below. The passage is still going, wide and low and more of the same with a view to another small collapse a few metres ahead. No sign of picking up Shitzentrasse yet or the passage growing in size. We've decided dragging spoil back the entire length would be near impossible so we'll continue over the coming weeks and months until we either find something, there's too much spoil to push aside or we need the drill. Sandy hole has already got enough horrible passage and we've just added another 20m with the prospect of more pretty high! The problem with these damn phreatics on Portland is that they tend to go a long way - if this one doesn't improve I'm certain we'll soon get bored with it.
I'll update this thread as the dig develops.
If anyone wants a dig - Shitzentrasse is up for grabs. I suspect it'll be exactly the same and probably lead to the same place ultimately.
North Passage in Sandy Hole is essentially the continuation of the entrance phreatic tunnel beyond the inkwell. This would have been an isolated phreatic running approx. 4 ft above the main North-South Passages in the cave had the bottom not fallen out of it where it intersects Gold & Silver Passage to create a junction. To demonstrate the point, only a few metres further ahead, North Passage passes directly over Paul's Progress. The vertical distance between the two can only be few inches, yet when in either passage you are blissfully unaware of the others existence. Until yesterday, North Passage ended at a calcited choke where it had been intersected by a much younger mass movement rift 26 m North East of the Inkwell, heading inland (shown on the survey below). 12 m North of North Passage is another small phreatic (Shitzentrasse) heading in a similar direction also ending choked at a rift on a similar longitude - presumably the same rift.
North Passage is an arduous flat out crawl varying from 3 to 5 ft wide, ending very cramped with little to no stacking space along it's entire length. The terminal choke consists of calcited infill. The Hardye's School CCF briefly had a go at digging this in the early 1970's not long after its discovery but made little progress due to the cramped conditions and loosing interest upon discovery of Ariel cave in 1974. Inevitably the choke would only be the width of the rift (approx. 2 ft), however as this is near the bottom of the limestone and the rift probably extends 20m above - like a good game of kerplunk, remove the wrong stone and there's a good chance of bringing down a lot of debris, making it a very long 2ft! To my knowledge, nobody has tried to dig North Passage since the 1970's and I dare say few have visited either.
The interest is fairly obvious - a downstream water worn passage, heading inland into an area beyond all known passages. The water obviously went somewhere and there's zero chance of that being a resurgence without crossing the entire island. Furthermore the existence of Shitzentrasse a few metres North gives hope the two passage will unite, as is seen at the confluence in Ariel Cave, resulting in an enlargement. Extrapolating further, wouldn't be it nice it they flowed into another (larger) inland North - South passage! This is very much one of those places that had it have been in a major caving region would have been pushed to a conclusion decades ago.
Sunday 5th Jan, myself and Dan set off to the end of North Passage to determine if there's any hope of passing the choke. Several knackering hours of mostly hammer and chisel work in an extremely constricted space, and at the point of more or less exhausting the limited places we had to loose spoil, we managed to open a small hole through the choke providing a view of the continuing passage. We were both too knackered to do anything about it so it had to wait until yesterday. Saturday 11th Jan - Mike K kindly agree to a trip to push the end with me on the promise of a certain breakthrough... It took Mike about 20 mins to enlarge the hole through the choke to a size we could pass but he was met on the far side with an extremely frustrating passage... Not quite big enough. The phreatic was approx. 18 inches high, 4 to 5 ft wide (sounds good) but with a 6 inch layer of extremely sticky mud in the floor and occasional rocks from either ceiling collapse or that had dropped down narrow rifts making easy progress impossible. If the passage was 6 inches higher or the mud not present we've have simply crawled ahead. Instead Mike spent the next 3 hours channelling a route through by pushing mud and rocks side ways whilst I followed behind further enlarging and improving the stacking to maximise space. We reckon we've more of less doubled the length of North Passage in doing this, perhaps adding around 20 m beyond the end shown in the survey below. The passage is still going, wide and low and more of the same with a view to another small collapse a few metres ahead. No sign of picking up Shitzentrasse yet or the passage growing in size. We've decided dragging spoil back the entire length would be near impossible so we'll continue over the coming weeks and months until we either find something, there's too much spoil to push aside or we need the drill. Sandy hole has already got enough horrible passage and we've just added another 20m with the prospect of more pretty high! The problem with these damn phreatics on Portland is that they tend to go a long way - if this one doesn't improve I'm certain we'll soon get bored with it.
I'll update this thread as the dig develops.
If anyone wants a dig - Shitzentrasse is up for grabs. I suspect it'll be exactly the same and probably lead to the same place ultimately.
