Sharbutt's 2

[tim.rose2]

It's about time I started a new thread about our latest dig - Sharbutt's 2 Rift.
Fairly predictably, Sharbutt's 2 is the second cave in Sharbutt's quarry. Sharbutt's Rift being the other and the 'top' entrance to Sandy Hole (must get round to updating that thread as well as some point). A bit of research suggests Sharbutt's 2 Rift might have historically been call 'Top Hole', first reported in the 1960's by Leicester University. No doubt other's may disagree on this as the historical info relating to Portland's caves is a bit open to interpretation. The name 'Top Hole' predates the discovery of Sandy Hole and so is not descriptive of a top entrance to Sandy (i.e. Sharbutt's Rift).

Whatever the name, the cave is a short but wide rift, high up in the limestone series approx. 10 m long and ending at a flowstone choke. Oh and full of Pigeons and their shit heap they've been creating for the last 50 years! Despite the slight whiff, it's been on our to do list for a few years but as is always the case, too many places to look at and too little time.

I need to start this story by rolling back approx. 18 months and beginning in Sharbutt's Rift, rather than Sharbutt's 2. I'd recently made a few modification to the Sharbutt's - Sandy connection to allow normal sized people through. Having never passed due to being fairly certain he'd not fit, I convinced Richard it was now probably big enough for him. We took some tools & drill just in case but quickly completed the through trip and out of Sandy. Now at a loose end for a couple of hours I convinced Richard to spend the rest of the day in Sharbutt's 2. We drilled through the flowstone blockage to find exactly what we expected - a wall of mud / rock infill. A couple of hours later we'd probably made about half a metre progress into this however in doing so we'd seriously pissed off some Pigeons which were less than impressed by our presence. We decided this should be a winter (rather than nesting season) dig and vowed to return in the Autumn.

November / December 2022 - myself and Richard had a couple more sessions digging out mud and rock but other than pushing the dig face back a couple of metres everything still looked the same. Unfortunately following that second trip Richard knackered his shoulder and has been unable to cave since (though I have heard in the last couple of weeks, it's better enough to get back underground again). So last winter passed with no further progress, the pigeons moved in for their annual pigeon nooky and that brings us to Autumn 2023.

20th Oct 2023 - Tom & I were at a loose end of a Friday evening and after something close to the car due to time being a bit tight to get to the chippy before it shuts so decided upon restarting the dig in Sharbutt's 2. Approx. 3 hours of muck removal yielded another metre forward. A week or so later Mike K and I spend an entire day in there ending with a hole opening giving a view of a few metres along the right hand wall. Not big enough to fit in, but at least something different to a wall of mud. The most significant bit was that a decent draft emanated from the hole and more so, it sounded like there was a much bigger draft somewhere ahead blowing through a gap. The downside of digging with Mike K is that everything quickly ends up 'Mike K sized'. On 11th November Mike R and I spent the day pushing ahead a little, but predominately increasing the diameter of the dig. Finally, last Friday, Tom and I had another session of digging both up and to the left at the end and also following the void found previously. I've a gut feeling which I can't really explain that up and to the left is better than following the void. I guess only time will tell. Currently we're around 5 to 6 metres from the starting point and things are looking reasonably promising. Plenty of potential with this one including good possibilities of a sensible pitch in the 10 to 15 m range and maybe even a connection into the rifts at the Northern end of Sandy. Hopefully we'll get a few more sessions into this over the coming weeks before Percy Pigeon and his bit of stuff returns to lay eggs and shit all over the place again.

Some photo's:
The entrance amongst blocks.

Me in the dig (Tom's photo).

Hmmm, not so clean (Mike's photo). This has since been enlarged!

 

[mrodoc]

Great work. Shows what can be done with some dedicated digging.

 

[tim.rose2]

About time for an update on this one.

Another 3 trips since I last wrote something. Myself and Tom had a session where we concentrated on the 'up and to the left' option. We kept getting whiffs of draught and very hollow sounding rocks but despite pushing forward a good metre nothing changed, just more muck and rock. We spent the end of that trip beginning to excavate the 'down and to the right' option and came to the conclusion this was probably more sensible as there was a void to follow. I should add this session was wet, drippy and the mud very sticky. We exited the cave damp and covered in mud. That should give a hint at what happened next...

Saturday 9th Dec - We had planned a trip to Wales for the weekend but that got cancelled. Text from Mike K... Sharbutts 2 then??? We'd just had a week of pretty heavy rain in Dorset. Based on the session with Tom my response was 'ok but you'll need your swimming trunks and goggles'. One thing Portland isn't known for is wet caving, but that was to change. Pretty much as I'd expected we found water pissing through the choke into our dig. We started by bailing around 120 L of water and then digging a trench to manage what was coming in. The muck absorbed the dripping water to produce a floor of liquid shite. Throughout the session we had water running down our channel back to the start of the dig and periodic bailing was required to make things slightly less unpleasant. Eventually we managed to make a bit of forward progress but emerged several hours later soaked through, coated from head to toe in mud and freezing cold. This was one we'll remember. Conclusion - best to avoid the place a for few days after heavy rain. We suspect this is the first time a cave on Portland has ever been bailed. What we did discover on this trip was an incredible 'wind noise' coming through some openings in our dig accompanied by an increase in draught. All good signs.

Sunday 24th Dec - Mike and I had a few hours spare in the afternoon so back to Sharbutts 2. Fortunately it's been fairly dry for a week or so. The mud was still pretty sloppy but at least it wasn't raining in the cave. Our trench had worked well and only 10 L or so had to be bailed from the dig before we started as well as the 15 tray loads of muck in the temporary spoil stashing spot left at the end of our previous session. The right hand dig was progressed forwards and downwards with Mike choosing to follow a void in the floor which in his words 'was like a pressure relief device going off' when a rock was moved. We now had a roaring noise, tonnes of draught, and this only seems to increase with every rock moved. Every new void / gap seems to be a new place the wind roars through. No sign of the 'black space' yet though. I cannot stress the volume of the wind noise in this dig enough. If this was up North the only explanation would be a mile of streamway, a 50 m waterfall and a huge chamber. Everyone would be creaming their pants. Unfortunately this is Portland and from experience we know this is just the wind hitting the cliffs and funnelling up the 'not terribly big' open rifts. Every breakthrough we've had has started with hearing / feeling the wind and so we're pretty convinced a breakthrough is now close. The rift is obviously choked where we're digging but a good metre or more wide so there's no reason not to believe it'll be cavable once through the choke. Although we've not found anything yet, due to the incredible noise we're experiencing we've named the choke 'white noise choke'.

I've not taken any photos as I don't think the camera would survive coming out of the box and so its use is being reserved for breakthrough day. Plus it's nothing more than a muddy dug tunnel in a choke at present. I suspect this one of the mess I had to clear up this morning will some it up nicely though...
For the record I prefer the digs we come out of clean & dry.

 

[mrodoc]

Keep up the good work.

 

[Pipster]

Thanks for the updates!

 

[Mr Dinwiddy]

About time for an update on this one.

Although we've not found anything yet, due to the incredible noise we're experiencing we've named the choke 'white noise choke'.

Thanks for taking the time to keep us updated on your various Portland digs Tim. Your careful description is appreciated and, like all digging threads, addictive. Happy New Year !

 

[tim.rose2]

Another update...
This place is getting frustrating! Since I wrote the last bit we've been back 4 times, twice Me & Tom, then Me, Tom & Mike K and finally last weekend Me & Mike R. We've installed a second drag tray and dug a 'chamber'. Meanwhile Percy Pigeon had visited between each session and shit all over our spoil heap, naughty Percy.
We've continued to follow down and to the right chasing the draught and associated voids from which it's emanating. Plenty of draught and loads of wind noise ahead on a blowy day. Unsurprisingly things sound calmer when there is settled conditions outside. I think we're approx. 3 m ahead of where Mike K first released 'the pressure relieve device' and no sign of the cave opening up yet. We're also managing to keep it a decent size. Until the last trip it was all muck and rock to remove however that has now changed. For the first time in this dig the drill came out on Sunday and between Mike R and I we drained 5 batteries destroying boulders with plug and feathers. At one point Mike got the best split either of us had ever seen... 3 P&Fs sunk straight into the middle of a washing machine sized boulder - normally that would be way to optimistic but this rock just seemed to be splitting well (we'd already taken quite a few chunks off of it) so we both agreed it was worth a try. As if by magic the damn thing fell perfectly into 3. All three parts were too big to move and in need of further splitting but this has certainly sped up the process. We drained the remainder of the batteries starting the process but the bulk of the three bits remain for next time. So what's behind the boulder? High up, more mud! Lower down is the draughting and noisy hole which we'll follow. Unfortunately the boulder pile is currently obscuring the view along this. The previous trip Tom had inserted a camera on a pole into the gap along the underside of the boulders we've since removed revealing what appeared to be more large, but clean boulders. I suspect the remains of Sunday's boulder bash will consume a couple of batteries next time before we get to the interesting bit. The downside of drilling is that the drill gets filthy; it took nearly an hour to clean it and 5 batteries. We can only hope these large boulders we're now encountering mark the end of the choke.

It still feels and looks like this one is nearly there, but we thought that four trips ago. I think this is also the longest rift choke found to date on the island. Typically they're only a few metres long but I think we're about 10 m and 13 session in now. To make matters worse we're on a ticking clock before Percy Pigeon and his team of Egg laying, shit flinging mates get settled in for the spring. I wonder whether plonking one of those plastic peregrines on a ledge just inside the entrance would help?

Plenty of optimism still, just a lack of time. I'm still hoping this is going to be our next success to announce!