Thou shall walk in Sandy Hole

[tim.rose2]

The story of our latest breakthrough...

For those unfamiliar with the wonderful caves on Portland I should first explain a little about Sandy Hole. Put simply it is a most hateful place. Despite being the longest cave on Portland and hosting the longest trip (approx. 7 hours for a there and back trip to the end of Ammonite Passage, so rumour has it), it is simply awful even for the most sadistic caver. The cave consist almost entire of phreatic tunnels 18 to 36 inches high littered with a chert, rock and sticky mud floor with pretty much zero in the way of formations. Connoisseurs of sore knees, bruises and awkward crawling who are not insane enough to head down Ammonite Passage can complete a short round trip which would take most about 90 mins to complete and features one of the few places in the cave it's possible to stand up (Worlds End Chamber). The only redeeming feature of the cave is that it forms the Southern part of the Blacknor through trip which visits a short but palatable section (Prize Day Passage & Gold and Silver Passage). This can be improved further by using the Sharbutt's rift entrance to cut off Prize Day Passage (the entrance tunnel).

I think this photo from several years ago sums up the cave quite nicely...

Despite it's minor drawbacks Sandy Hole has almost certainly attracted more attention from diggers than any other cave on Portland. So like many before me I eyed up a spot within the cave to find caverns measureless to man.

Roll back a couple of months, on a day when Mike, Gaynam and I met of Portland. I'd already announced there was a site in Sandy I wanted to look at, Gaynam stated he'd never been down Sharbutts and uttered the words "I'm sure Sandy can't be as bad as I remember" (insert loud witches cackle). Where I took the two was the Northern most point in Sandy at the far end of the rift which forms the connection to Vortex Passage in Ariel Cave. The (as far as I'm aware) unnamed rift is of good size and ended at a flowstone constriction with a view of a couple of metres beyond, being not to dissimilar to the end of Persil before we attacked that back in 2020. It took a couple of hours but enough was eventually removed on that occasion to let Mike pass. Unfortunately the continuing rift was barely 'Mike sized' immediately got a tad smaller and progress impossible. We looked at a potential up and over but decided to leave that for another day.

The 'another day' was 22nd July. Mike and I set off down Sharbutts with 2 drills, 8 batteries and an assortment of bashing tools. First job was to make the gap through the flowstone a bit bigger and secondly remove a couple of stal'd in blocks above head height beyond which it appeared a little wider. It turned out it was a little wider but only for a couple of metres. As with the lower option it quickly became too tight. Despite not finding any significant passage we did find some pretties above our heads including a few translucent straws which I've never seen on Portland before. Straws are typically orange or yellow:

About to give up as a bad idea Mike decided to have a look at the floor prior to the flowstone. There was certainly gaps amongst the boulders but I certainly didn't share his optimism for there being a route underneath. We decided that before leaving we would spend 30 mins shifting rocks and see what happened. Suddenly things started to look more interesting with an intriguing, drafting hole appearing down and to the right. Knackered, but excited we left forming a plan to return. Two days later, equipped with heavy tackle sacks the two of us made our way along Gold and Silver Passage to once again find Sandy's Northern end. We had move a fair amount of rock including splitting a few before the main event began. A mammoth sized boulder lay between us and the void we could now clearly see below. Several hours later having exhausted 8 drill batteries, then ourselves with the 'desperation hammering' the boulder had beaten us. It was this return trip (now in our third visit to Sandy in under 2 months) back along Gold and Silver and out the entrance tunnel whilst totally knackered that really cemented our hatred of this cave. We just simply had to make the damn place better. Pictures from left to right; 1. what remained at the end of the day, 2. desperation hammering, 3. peering down the hole.

The photos don't show the full extent of the boulder as the other half is buried below floor level and the far side cemented with flowstone to the back wall. To give an idea of how much we'd moved the floor when we started was about a foot above Mike's head in the first photo. The very first drafting gap we peered down was the small hole right in the very top right hand corner of that photo the other side of the flowstone bridge linking the two walls.

Move forward a couple of weeks to 07/08/22 - we both had a free day to return to Sandy. We went through another 5 batteries on that damn rock but it eventually succumbed. Unfortunately the gap wasn't quite big enough. A bit of chipping away here and there and Mike was through. A little more and the fatty of the team (me) could fit as well. Time to explore....

Breaking news; thou shall walk in Sandy Hole. We'd broken into a very sizable section of rift which was much wider at this lower level. This is certainly one of the widest known rifts on the island. Soon the rift opened to the full height which must be at least 10 m. Unfortunately after what we estimate to be only 20 m the next flowstone / infill blockage was found. Mike did a bit of climbing but it didn't look like there was a route over. It looks diggable but it won't be a quick win (my guess a few trips). Back at the breakthrough point passage can be followed for approx. 10 m back underneath much dodgyness to end at a choke. This would be somewhere under the route to the dig so not worth bothering with. Although only a modest gain the new section is a respectable size, hosts a few pretties and has good potential to yield more cave. The breakthrough point is still snug and needs a bit more work when we next return. In total we estimate an additional 30 m has been added to the cave length.

The breakthrough point

The great abyss beyond

All Portland rift have one (well at least one!)

 

[tim.rose2]

A few more photos:

The next boulder / flowstone blockage. We actually think the best place to dig is in the floor a couple metres prior to this to create a route underneath.

Checking for a route over the top (apparently it's a bit brown trousery up there).

Just beyond the breakthrough point

There shall be cave pearls to delight ones eyes

Danglies

 

[Cavematt]

An awesome story of determination in a not well-known caving area! Thanks for sharing, Tim, and a nice followup to the online talk from last year. These teasing breakthroughs help keep the enthusiasm going

Fingers crossed you have accessed a part of the system with more discoveries to be made.

Some great breakthrough day snaps there (often the best kind). Looks terrifyingly like the North York Moors windypits where some sliprifts have been modified by water long after their formation by land movement. But I presume your new rift is mostly water-formed?

 

[Pipster]

Brilliant!

 

[mrodoc]

Congratulations! It shows what perseverance can achieve. And I agree Sandy is a bit grovelly but it does have some interesting fossils. The climb to get in is a bit of a so and so unless it has changed again.

 

[tim.rose2]

"Bit grovelly", there's an understatement.

The rifts on Portland are a little different in that they're relatively young. The phreatic's are much older and there's numerous examples of where the phreatic tunnel was the likely weakness that caused the rift to form in that particular spot. There's no surface streams as such on Portland and only 'drippy' water underground so there's very little water modification to the rifts - most of the walls have matching features opposite each other. The flowstone is mostly found in the rifts and typically coats mud banks / collapsed rocks / infill etc, kindly cementing together many of the places you'd want to dig!

As for this new rift - bit of a mystery really. No real evidence of being waterworn however I'm struggling to see how some of it could form by mass movement either. The section where the photo shows Mike climbing is typical Portland rift, but the bit before that is not. There's another similar bit back before our breakthrough where the connection to Ariel is; wide area below a flat roof with the much narrower rift up to the left. The flat roof bits looking very much like some of the water worn passage in Ariel.

We don't really know where this rift is heading. The section before is probably un-surveyed and definitely not published if it has been. Obviously our new bit is un-surveyed at the moment too. My gut feeling is that it might be heading roughly North a little inland from Brownsea Island chamber which is the end of the water worn passage in Ariel. Again, very much gut feeling, but I'd guess that another 30 m might take us quite close and that would certainly be an interesting area to get to. Currently nobody knows where the water went beyond Brownsea; Some speculate there is an unknown hydrological connection to Sandy whilst I believe the two sets of water worn passage are unconnected and only joined by mass movement rifts. That leaves both upstream Sandy and downstream Ariel yet to be found. Brownsea Island chamber is another place I've considered digging, the problem being that it's a long jaunt to get to and taking a bag of tools would be interesting.

This one is certainly worth a little more attention yet.

 

[mikekushy]

"Bit grovelly", there's an understatement.

The rifts on Portland are a little different in that they're relatively young. The phreatic's are much older and there's numerous examples of where the phreatic tunnel was the likely weakness that caused the rift to form in that particular spot. There's no surface streams as such on Portland and only 'drippy' water underground so there's very little water modification to the rifts - most of the walls have matching features opposite each other. The flowstone is mostly found in the rifts and typically coats mud banks / collapsed rocks / infill etc, kindly cementing together many of the places you'd want to dig!

As for this new rift - bit of a mystery really. No real evidence of being waterworn however I'm struggling to see how some of it could form by mass movement either. The section where the photo shows Mike climbing is typical Portland rift, but the bit before that is not. There's another similar bit back before our breakthrough where the connection to Ariel is; wide area below a flat roof with the much narrower rift up to the left. The flat roof bits looking very much like some of the water worn passage in Ariel.

We don't really know where this rift is heading. The section before is probably un-surveyed and definitely not published if it has been. Obviously our new bit is un-surveyed at the moment too. My gut feeling is that it might be heading roughly North a little inland from Brownsea Island chamber which is the end of the water worn passage in Ariel. Again, very much gut feeling, but I'd guess that another 30 m might take us quite close and that would certainly be an interesting area to get to. Currently nobody knows where the water went beyond Brownsea; Some speculate there is an unknown hydrological connection to Sandy whilst I believe the two sets of water worn passage are unconnected and only joined by mass movement rifts. That leaves both upstream Sandy and downstream Ariel yet to be found. Brownsea Island chamber is another place I've considered digging, the problem being that it's a long jaunt to get to and taking a bag of tools would be interesting.

This one is certainly worth a little more attention yet.

I find it bizarre how a rift this wide with a solid ceiling can open up so low down from the surface, being under such an immense load.

Fair enough if there’s a chert band above it, but the nearest chert band we discovered was about 5-6m below the wide section of rift we first entered.

Very bizarre place and as Tim says there has to be more to this.

 

[mrodoc]

Yes, Brownsea Island chamber is interesting. Looked like a fossil sump chamber to me but my memory may be at fault. Looks like a winter visit with a camera is indicated - after some more weight loss!

 

[tim.rose2]

The easiest way into Sandy now is Sharbutts. The squeeze is significantly larger than it used to be. 20 m rope as a handline. The easiest way out is not Sharbutts! Currently there is a handline on Sandy entrance. I'm intending to leave the route into our new rift a sensible size (it isn't at the moment) and there are no tight bits on route from Sandy / Sharbutts entrances so pies can still be consumed.

 

[NigelG]

Only just read that, three months later!

Well done, Tim, Kushy and Gaynam.

The ancient stream passages are all joint-controlled although those in Ariel (or Blacknor) caved have the added spice of a chert aquiclude as the roof. I have not heard of any cave anywhere else with this sort of "upside down" control; but would be happy to know of such .

The mass-movement rifts are all along joints, and some happen to have exploited the same joints as the phreatic passages had.

There is some limited but significant vadose development in Portland, notably in Ariel. This and Sandy Hole (assumed one cave with no passable connection through the original streamways) both show signs of rejuvenation. The upper levels down-cut to create quite definite nick-points acrss the system; while Sandy Hole has roof-pockets filled with coarsely-granular sediment apparently remaining after passage infills have been washed out.

There remains another enigma in "old" Sandy Hole. This is, what happens to the East of the known cave's main N-S drag?

North Passage (which heads East then turns South) is paralleled by Schitzenstrasse and a fairly broad but 'orribly low, un-named, unexplored "passage" near the small World's End chamber.

North Passage: draughts, is blocked by calcited boulders, probably in a cross-rift. Hardy's School Combined Cadet Force cavers were digging that in the very early days of exploratory caving on Portland (late 1960s-early 1970s).

Schitzenstrasse (apt name: very low and muddy) leads from World's End, ends choked, probably too small to dig. Besides, digging would lose some of the few stalactites in the place, and risk breaking a lovely pendant ammonite whorl on its ceiling.

The un-named thing might yield to a very determined Team Ferret (so not me!) scraping the marl off its floor to gain an agoraphobic extra inch or so of height. Peering into it, I could see no definite "end" and its floor seems to drop away maybe ten feet ahead (estimated).

This trio of passages might only be old inlets, but... Ali Moody once wrote that "caves have their own agendas". She was referring to Charterhouse Cave, but Sandy Hole has agendas all of its own.

'

[The cave's name was given by the discoverers having grit blowing into their eyes as they dug through the little choke just inside, to enter Prize Day Passage. That has its own tale that alleges they were supposed to have been at some works award ceremony that day, but had better things to do, like awarding themselves the "Best New Cave" prize. The system was explored separately but co-operatively by HSCCF and the fledgling Dorset Caving Group; with the connection from Ariel and the continuation of Ammonite Passage falling to Mike Read and pals in the 1980s. The route from the entrance to that present Southerly extremity is perhaps the country's longest continuous crawl, not tight but varying from roomy flat-out to hand-and-knees, nearing a mile in total to an obstructing boulder someone might like to clear. (Don't look at me.) A collector's piece..... ]

 

[tim.rose2]

Since starting this thread, myself, Sas & Mike have made two further trips, the most recent being yesterday. The first was to enlarge the breakthrough point to a more sensible size and begin digging at the new Northern limit of the cave. The second, yesterday, was to survey the find (and enough of Sandy to use as reference point) and to continue digging at the end. Nothing much to report on the digging front other than we're now 3 m into the choke with no sign of the flowstone'd boulders ending yet.

The survey, however, is certainly intriguing. As expected the passage runs roughly North and inland of all known cave. The find added 28 m heading North from the breakthrough point with an estimate (we couldn't be bothered to survey it) 10 to 12 m heading South underneath the route in. So our discovery adds about 40 m to the cave. We're only 17 m from Brownsea Island (the end of the water worn passage in Ariel) horizontally and I'd estimate 2 to 5 m lower. I suspect our rift is something unrelated heading north but there's certainly potential here to intersect water worn cave or even forge a connection to Brownsea Island which would bypass Squeezy rift on the through trip. We're a little mystified by some of the features in the rift and have certainly considered it's indeed part water worn so it's possible our passage is the continuation of the water worn cave which has been mostly obliterated when the rift formed. Only time & digging will tell!!!

This picture shows the location of the new rift and Brownsea Island, and their relationship to the significant Westcliff caves.

The final observation from yesterday - it turns out Sandy Hole can get rather damp under the right conditions. I've certainly known it a bit drippy at times but yesterday the place was horrible. Sharbutts rift was running with water and 'well greased' - the decent was quite swift. As as for our new rift, it was basically raining indoors. We left the cave soaked through and cold, which is a rarity. It's normal to leave Portland's caves sweating and trying not to overheat. This made the cave even worse than normal. We all love Sandy Hole really.