Author Topic: Digging in Showerbath Cave, Portland  (Read 3284 times)

Offline tim.rose2

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Digging in Showerbath Cave, Portland
« on: April 01, 2018, 10:45:49 pm »
We had planned a long weekend in either Yorkshire or Derbyshire over Easter however changed plans due to the weather.  Thursday / Friday we spent caving on Mendip (Spider & Manor Farm).  Saturday / Sunday we headed to Portland for either caving / climbing as the weather allowed.  Jump back a few weeks, following one of my recent trips to Steve's Endeavour myself and Richard stumbled across Showerbath Cave - a short section of pheatic passage ending at a too tight choke.  Another place I've been meaning to look at for years.  Shift a boulder 6 inches and a view of the pheatic tunnel continuing beyond appeared.  Seems like this was not noticed by Portland diggers of the past. 

As much as I know little about or have little interest in digging caves this seemed to easy to ignore, particularly as Portland could do with another cave or two appearing.  So Saturday pm, once the rain cleared up, myself and Sas went to have a look at what could be done.  Armed with a selection of 'might be useful tools' we wandered up the cliff.  We busted up a few boulders which were in the way (presumably left by previous diggers) and tossed them out the entrance.  Turns out an SDS drill, lump hammer and a set of plug and feathers can be satisfyingly destructive.   Time was tight (appointment in the pub) and the drill battery was dead so we gave up.

Having been surprisingly productive Saturday, Sunday we decided to go back for more and hopefully find miles of walking sized passage (some chance on Portland!). 

One final boulder was bust up to give a free run for a drag tray to the entrance from the dig face.  Turns out my garden hoe is an excellent weapon for scraping out mud.  By lunchtime enough mud / rock infill was removed to fit through.  Some wood was inserted to support a dodgy boulder.  Sas went first and soon returned to report the passage beyond was sufficiently filled with mud to prevent progress.  Me next with some tools - a couple hours later I'd chucked tonnes of soil down a rift, created a turning circle and worked along to the next annoying rocks.  Unfortunately these might be holding up the ceiling but the passage beyond looks bigger and less filled with mud.  All in all about 5 to 10m of passage gained, still with a view beyond.  That was nearly enough for the day.  Last job, one final look at that dodgy boulder - might as well use up the remaining drill battery me thinks!  Let me have the plug and feathers - crack, and down half of it comes.  Pokey pokey with a crowbar and the rest is down too.  Ok, we've left the cave blocked in the place it was when we started but 30min effort next time should have that cleared and we'll get to discover 5 to 10m of passage a second time - this time big enough to fit through.  Hopefully taking this boulder out will remove the squeeze beneath it and make it easier to remove a few larger rocks (which won't fit down the rift I'd been chucking the mud) from the passage beyond.

A couple of pictures...

Before we started today:



Me finishing digging out spoil:



Sas first through into the new passage:



The dodgy boulder:


Half the dodgy boulder on the floor and then cut in half:



And then it was gone:



Richard wanted a garden outside the entrance to cultivate his wild cabbages in, perhaps not the design he would have been thinking of but we have provided a patio and veggie patch:



Providing I can work out how to get beyond without bring the roof down on me we're going to have another go at this in the coming weeks as it still feels worthwhile.  Unfortunately removing one dodgy boulder has made the next look dodgy so this might have to come out as well before getting back to the end.

If anyone wants to help / put in the effort so I don't have too please get in touch.  I'd like another cave on Portland to play in but more than happy for someone else to find it!

Offline Pegasus

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Re: Digging in Showerbath Cave, Portland
« Reply #1 on: April 01, 2018, 10:53:41 pm »


 :o :o :o :o ;D

Offline mrodoc

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Re: Digging in Showerbath Cave, Portland
« Reply #2 on: April 02, 2018, 05:17:15 pm »
And I thought our dig looked dodgy!

Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #3 on: April 02, 2018, 06:07:21 pm »
The dodgy boulder was pretty well wedged and with the support underneath it wasn't going anywhere.  We decided to remove it to improve access beyond.  There's many boulders on Mendip regularly passed under which look much worse.

The loose stuff here is where the rock has fractured (there's a 4 to 6 inch rift on the left hand side not visible in the photos) after the pheatic tunnel was formed and resulted in the tunnel roof becoming dodgy and collapsing.  Further ahead the tunnel appears to start moving away from the rift (right handed) with the left hand wall coming back into existence and the roof looking much better (well as good as they get on Portland).  I'm working on the theory once the pheatic tunnel moves away from the rift there should be less fill and less collapses.  If things don't quickly improve this will be put on hold as I have a couple other places on Portland to look at which might yield new cave with little effort.

I spent a bit of time last night looking at this on Google earth.  Should the cave continue in the same direction it's heading straight into the area North of Sandy hole on the same level as Sandy.  One thing we were wondering is whether the water flowed in / out.  If out I'm expecting the cave only to get smaller.  If in, there's hope its a tributary to something else (possibly Sandy).  There is scalloping, however there seem to be examples which go both ways!  Neither of us could convince ourselves which way the water flowed.  Anyone have any tips to sort this out?   
 

Offline mikem

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Re: Digging in Showerbath Cave, Portland
« Reply #4 on: April 03, 2018, 07:27:53 am »
If it was hardly flowing then you are seeing phreatic pockets rather than scallops.

Mike

Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #5 on: April 03, 2018, 01:31:41 pm »
Apologies for my ignorance but what is a phreatic pocket / how is it different to a scallop?  Google gives no clues!
Cheers
Tim

Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #6 on: April 08, 2018, 10:06:05 pm »
Well we've had another play in Showerbath today.  Turns out bringing the roof down only generated more dodgy looking boulders!  We cleared the previous pile and then created another out of the next bit of the roof.  I'm not certain this is the best approach as it's hard work and we seem to be gaining very little at a time.  Propping with bits of wood and gingerly crawling underneath certain yielded quicker progress!  Unfortunately the most recent two bits of roof we brought down are not only blocking the way ahead we found last time but also sufficiently wedged leaving me wondering how to get them out without having to remove all the stuff on the left.  We'd ran out of drill battery by this point but will try breaking up with plug and feathers next time and hope being smaller will allow them to be wrestled out.  Annoyingly the next bit of roof is also hanging death so I guess that'll have to be brought down too.  I had remembered the roof looking more solid beyond so hopefully we'll soon see something I'd be prepared to crawl under again.

Couple of pictures...





As an aside, we noticed today the spoil heap from our efforts over Easter had been rain washed to reveal a substantial number of the rocks were in fact as per the photo below.  I've no idea what it is, but it's very fragile and rather pretty.  The photo is of a bit I brought home and cleaned up.  Anyone able to identify what I'm looking at?  The entire piece is approx. 3cm across.  There was also quite a few bits of broken orange / yellow Portland flowstone.  All the spoil was 'mud & stone' scrapped out of the floor so I guess both the broken bits of flow stone and what ever the above is must have flowed in at some point?





Offline droid

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Re: Digging in Showerbath Cave, Portland
« Reply #7 on: April 09, 2018, 09:45:34 am »
Dog-tooth spar?

Probably way off the mark mind.... :lol:
No longer 'Exceptionally antagonistic' 'Deliberately inflammatory'

Offline mikem

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Re: Digging in Showerbath Cave, Portland
« Reply #8 on: April 09, 2018, 10:05:03 am »
Apologies for my ignorance but what is a phreatic pocket / how is it different to a scallop?  Google gives no clues!
Cheers
Tim

Scallops are caused by flowing water, thus indicating direction, whilst pockets are caused by stationary water, giving no distinctive edges - but they are 2 points on a continuum.

Mike

Offline JasonC

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Re: Digging in Showerbath Cave, Portland
« Reply #9 on: April 09, 2018, 02:07:45 pm »
If those stones are up to the general quality of Portland stone, you may be able to start a sideline in micro-quarrying...  :)
If nothing else, if you pop up to PSQT, you may find some stone-carvers eager to take them off your hands
Just a thought...

Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #10 on: April 09, 2018, 07:37:57 pm »
The scallops / pheatic pockets appear to be directional - just some seem to go each.  I suspect it's just my poor eye for should things!  Hopefully this situation will become clearer when we eventually get to have a look in the passage I've seen ahead.

Regarding the stone - we're currently working on a patio outside the cave to give us a nice place to sit and have lunch.

Offline AR

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Re: Digging in Showerbath Cave, Portland
« Reply #11 on: April 09, 2018, 09:00:46 pm »
Dog-tooth spar?
[/quote

Looks more like Selenite or perhaps Aragonite, to my eye.
Dirty old mines need love too....

Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #12 on: April 22, 2018, 11:10:04 pm »
More fun in Showerbath on Saturday 21st April...

Job no. 1 get those x-ceiling boulders out we left jammed blocking the way ahead last time.  Having failed miserably to shift them with a crowbar on the previous session this time we went equipped with a new toy - £9.50 scissor jack from ebay.  This proved very effective and in little time both boulders were out of the way and then broken up with plug and feathers appropriately to evict from the cave. 

Job no. 2, a thorough assessment of the next ceiling boulder showed it was better wedged than perhaps looking at it head on suggests.  With convenient ledges on both side we decided this could be propped - initially with wood as we had some but a more permanent arrangement will follow should the cave become worthwhile. 

Job no. 3, we dug out the floor a bit more to allow easy access underneath and wedged a load of stones into the boulders on the left to help support that load of choss.  We've now got a much better route into the 'new' bit of cave found on our first trip.   

Job no. 4, some more floor scrapping was conducted to improve the size of the tunnel beyond and a couple of meters of progress was made into the mud fill.  Some more stone wedging was required to support the roof at the current dig face.

It looks like there's approx. 1 more horizontal meter of mud to work through before person sized passage is entered.  Unfortunately there are a couple of rocks in amongst this which might be holding up the ceiling!  Providing the ceiling doesn't descend one more trip and we should be through.  This will make or break this cave.  Should we only find another short section before more mud infill / collapsed ceiling then we'll put this on hold for a while and look at some other sites on the island.  On a positive note there was a good draft emanating from the hole in front of us and the cave has now doubled in length!

The photos - very poor this time as they were done on my phone.  The current caving camera (I buy second hand cameras for £20 on ebay and treat them as disposable) decided to die despite working fine when tested at home before we left!

The original breakthrough point now with temporary support


The current dig face.  The hole in the centre of the photo is where we be going.


Sas evicting my latest tray of dirt. 


Our amazing patio outside the entrance.

Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #13 on: April 29, 2018, 10:37:37 pm »
Another session in Showerbath on Saturday.  This time there was 4 of us, Me, Richard, Nick & Sam.  With the additional people we were able to shift a huge amount of mud and rock, much of it out the entrance.  The passage beyond the supported boulder in previous photo's has been properly cleared out to improve access and give more space to work as this is looking like a longer term job than initially expected (i.e. hoped).  We also took the nose off the rock sticking out under the supported boulders so that we can get a tray down to the dig face to remove rocks more easily.  At the dig face a bit of ceiling was removed which looked dodgy and the infill of a mixture of mud and rocks shifted as far as two large boulders blocking the way.  These will need breaking up as they are too big to shift so this will wait until next time.  Looking beyond these boulders the pheatic passage clearly continues but is 2/3rd full of rock / mud as far as I could see.  Once the boulders are out it should be possible to make reasonably quick progress again.  This trip moved the dig face approx 3m further ahead however the biggest win was improving the access.  No photo's this time.

Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #14 on: May 28, 2018, 11:20:58 pm »
Two more sessions in Showerbath this weekend resulting in a breakthrough...

Sas and I met Nick and Sam on Sunday morning at 11:00 with the plan of attacking Showerbath.  As with the previous trip a team of 4 proved most effective.  Myself and Nick working up front digging out a mixture of dirt and rocks whilst Sas and Sam managed spoil removal.  The first job was to replace the wood support under dodgy boulder no. 1 with some scaffold Nick had obtained.



Next was to deal with the boulders blocking the way ahead.  Despite appearances, the lower and smaller boulder didn't appear to be holding up the one above so this was removed and escorted out of the entrance.  We then dug out the floor with ease to provide a route underneath the larger boulder above deciding it was sufficiently wedged to ignore for now.  Many more piles of dirt and rocks later we'd worked our way another meter or so along the passage.  Dirt was poured down the rift we've been filling and rocks were evicted from the cave.  This was all with the aid of the mark three drag tray fashioned out of a carpet tile.  A new unit of measure was born, the 'carpet load'. 



We eventually gave up at 4:30 went our own ways for food and then met up for a wander down to Red Door Tunnel, some rock hopping and to show Nick another potential dig site in the evening.

Following a successful Sunday, we decided to meet at 10am Monday morning for another session.  Many more carpet loads shifted.  A route under dodgy boulder no.2 was engineered and a support added for peace of mind.  We now had a view of what appear to be an inland (right hand) turn in the phreatic passage whilst the narrow rift which had been running alongside the tunnel continuing ahead.  Nick working at the end under the boulder of impending death...



Unfortunately digging became awkward; my "we'll be through in 30 mins" turned into a couple of hours.  Right on the corner was a mix of compacted rock and mud overlaid with calcite.  This effort culminated with a tricky operation to drill and break off a sizeable lump of rock with plug and feathers in a very constricted space whilst led under dodgy boulder no.2.

Eventually it was possible to get through into 'open' passage.  I made my way along a tight tunnel heading inland until a pile of rocks was met.  If I'd still had energy these could have been moved today but it was decided this would be for next time.  The passage continues open beyond.  Unfortunately no turning spot was found so the pleasure of retreating in reverse was necessary.  Nick then took a turn to reach the boulder pile and inspect our find.  Sounds of enjoyment were heard (particularly when tackling the reversing).  Sas peered around the corner and ventured no further whilst Sam decided the sunshine was preferable. 

Having moved away from the rift the tunnel roof looks far more stable.  There is also a huge draft which is visibly blowing around cob webs and dangling roots.

We measured the length of the cave: 
To the old end was 8m. 
From the entrance, through the dig into the new passage as far as the boulder pile measures 30m so our efforts have produced an extra 22 m of cave.  Probably the first new cave for a couple of decades on Portland and there are many more meters visible yet to be entered.

More pictures...

Group photo outside the entrance


Looking back along the dug tunnel


Looking back along the new 'open' passage


Nick enjoying the reversing from the new passage


With weather like this, what the bloody hell are we doing!  This is the view stood on the spoil heap outside the entrance.


The spoil heap


No doubt many will ask why we are bothering given that the prospects are only shitty little tunnels to crawl in and perhaps a rift to stand in if we're lucky - well I need a new cave to play in on the island and we're mad.  Anyone interest in helping?  There's no shortage of dig sites.

Offline Ian Ball

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Re: Digging in Showerbath Cave, Portland
« Reply #15 on: May 29, 2018, 08:29:10 am »
"Support added for peace of mind"

 :'(


Think I'll stick to GG!

Offline mrodoc

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Re: Digging in Showerbath Cave, Portland
« Reply #16 on: May 31, 2018, 09:28:37 am »
Keep digging, you never know what you might find.

Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #17 on: June 16, 2018, 11:18:45 pm »
Another day in Showerbath today...
Four of us - Myself, Sas, Nick & Steve.  Today's plan was to sort out the roof & awkward corner at our previous breakthrough point.  Unfortunately to progress this cave further it was decided we needed both more room and improved roof stability.  The piece of wood used to prop dodgy boulder no. 2 was removed and then the dodgy boulder itself was attacked.  Without too much effort it cracked into 3 using a combination of plug and feathers, hammer and chisel.  It then took considerable effort to get them to drop!  Once down they were broken up to manageable boulders and all but one evicted out the cave.  Unfortunately we ran out of drill battery with one further plug and feathers break required - the remaining boulder simply being too big to fit out.  Some floor on the corner was removed and then the next bit of roof poked - it moved, bugger!  Bit more poking and most of it was down and once again the way on blocked.  Gave up for the day!  Fortunately the roof beyond this corner is completely stable so once these are out (next trip) there is no more ceiling to attack.  Feels like negative progress, however today's efforts will make progress in the new & open (yet rather small) passage beyond much easier and safer.  If not the next trip, the one after should have something more interesting to write about!

The one remaining boulder awaiting breaking up:

Offline NigelG

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Re: Digging in Showerbath Cave, Portland
« Reply #18 on: July 16, 2018, 07:04:44 pm »
Nice effort, Tim & Co!

The more obscure Westcliff caves like Showerbath didn't really yield to the earlier diggers (principally Dorset Caving Group, of which I was a member) in the 1970s-80s, for a mixture of reasons. Not having the luxury of things like battery drills, limited experience of dealing safely with boulders and boulder ruckles, the diggers themselves eroding away or calcifying or something, and large Undercliff slips destroying the "path".

In time most of the 1980s effort went into Ariel Cave, Sandy Hole, then the Grove Cliff Caves network.

Also of course there are few dedicated, exploration-minded cavers in the area - and they tend to prefer turning Mendip or South Wales inside out, to Portland.  Until your team came along, there was quite a long stasis because no-one was able to put together a digging team on the Island. 

I was actively digging on Portland with two others for quite a while in the mid-1980s, finding Skittle Alley, emptying Allotment Dig and starting to empty the rift within to try to find Coffin Hole's postulated continuation below it; but of our team, Martin gave up caving and Phil emigrated to New Zealand! (Was the dig that bad, Phil?)

++++

That lovely calcite formation may have formed in a pool.

Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #19 on: July 16, 2018, 07:44:36 pm »
Well we'd certainly have struggled in Showerbath without the SDS drill.  I've long since lost count of the number of boulders drilled and split with P&F.  Everything else was by hand though.  We also have a lot to thank the local climbers for.  Since the explosion of climbing on Portland over the last 20 years we now have well maintained paths / routes to all our caves.  The climbers have a set up the Dorset Bolt Fund to assist with the finances for path maintenance and new bolting.  It would be good if cavers using these paths considered a small donation occasionally.

What would be good is if we could get more than one digging team together!  There's loads of places to look and a fair bit of work to try to save a few of the existing caves from being lost.




Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #20 on: July 22, 2018, 10:26:48 pm »
Another couple of hours in Showerbath on Saturday - Myself, Sas, Nick & Sam being the team.

First job was to reduce the boulder left from the last trip.  Secondly the last couple of roof boulders blocking the way on were un-wedged and reduced in size.  Nick took the broken rocks back to the original breakthrough point, whilst Sas and Sam managed the evictions from the entrance.

Next I decided to make the awkward corner considerably less awkward.  This produced a load more spoil much to everyone's delight.  We were back into the new passage.  Myself and Nick took turns to work along the new bit, chucking back any rocks which were annoying.  It's tight and as yet there is no turning point.  Nick then stacked a few rocks on the shelving and continued passed our previous limit of exploration for a few metres.  He stopped at an awkward slab in the floor which needs to come out to make life easier.  Essentially the end is open at present with a view of approx. 10m.  Nick's also hopeful a turning spot might exist about 5m on.  Unfortunately it was time to leave - Wellington Hole awaited (see other thread)!

The next trip should be interesting & we'll be reporting an increase in the length of the cave.

I'm afraid no photo's this time.  Having trashed a camera by lying on it whilst messing around in another cave before heading the Wellington on Friday I didn't want to tempt fate and do the same again.

Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #21 on: August 11, 2018, 07:06:32 pm »
Another few hours in Showerbath today - just myself and Richard this time.

Since my previous report Richard (our cave fairy) had been into Showerbath and done some spoil clearing left over from the previous trip, so a nice clean starting point again.

Today between the two of us we shift 15 tray loads of rocks and 1 large boulder from the 'new' bit of the cave.  This included the majority of what Nick had previously stacked along the shelving, the awkward slab which marked the previous limit of exploration (the boulder), the remains of the pile of stones at which we'd previous measure the length of the cave too and a selection of loose stuff out the ceiling.  In doing so I've managed to make a turning area (for small people) approx. 10 m beyond the last place, this allowed the first few non-reversing trips to 'nearly the end'.

All this allowed better access beyond Nick's previous stopping point to assess what's next.  Approx. 4m beyond, the floor becomes 'calcited mud' and raised towards the ceiling making further progress impossible.  As always with Showerbath the blockage is no more than a couple of metres long with a view to a few more metres of open but tight passage beyond.  We've dealt with this calcited mud in one previous area in the cave and it's a bloody nightmare.  Furthermore there's bugger all room to move.  We think the next job is going to be a massive effort to lower the floor (mud infill) all the way from the breakthrough corner to the end to provide more room to attack this blockage and make spoil removal significantly easier. 

Given that we have a definitive 'end of the cave' at present and that it's become hard work we'll probably park this one for a while and go look at some other sites for a bit.  Life gets stale if you keep going back to the same place.

I've not measured to the end, however I would estimate the total cave length now to be 40m.  So in 9 digging sessions over 5 months we've added a good 30+m to the cave.  There's still a draft coming from the end and a view to 'open' passage.  The cave took a couple of 90° bends creating a dog leg of about 5 m but the passage is still roughly following the cliff line (I think).


Offline mikem

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Re: Digging in Showerbath Cave, Portland
« Reply #22 on: August 16, 2018, 06:40:58 am »
Have you looked further along the cliff for other holes it might connect to?

Mike

Offline tim.rose2

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Re: Digging in Showerbath Cave, Portland
« Reply #23 on: August 16, 2018, 11:01:43 pm »
There's nothing obvious which can be seen from the path running below the cliff but a more thorough inspection could well be worthwhile (along with the whole cliff line down to Wallsend cove the other way).  The draft could well be emanating from a too tight rift connecting to the cliff beyond the current limit - there's plenty of these.  I think we've already passed 3 or 4 in the cave which I'm pretty certain all link to features on the cliff.  For the moment though the draft is definitely coming along the tunnel.  I don't think we're heading towards any known part of Sandy either (which does have a gale blowing through it).