Talk about Portland's Caves

[Ed W]

Great introduction to caving on Portland Tim.

Having been to the bitter end of Sandy Hole on a number of occasions I can add a little more detail.

The cave has been surveyed, and the survey inconsistencies were sorted and the end radio located.  The survey was completed before the end of the Century but has to my knowledge has never been published.  I understand that the far reaches of the cave have turned distinctly left / east away from the cliffs on the west coast and towards the dry valley leading from Sweethill towards Culverwell (the source of the only stream on the island)

The cave is more complex than shown, with several oxbows and splits into two branches at the end (probably the start of another oxbow).  The passage is quite large in places, annoyingly no higher but several metres wide in some places.  There are also several tiny "avens" (too small to get into) that penetrate through the chert band that forms the passage roof (and supplies the razor sharp splinters that are impregnated into the mud).  There are even some very nice formations in out of the way places if you know where to look. 

It takes about 4 hours to reach the end, and my longest trip was over 17 hours.  This included surveying and exploration (discovery of Apology Passage - we were sorry we found it).  There are still "open" leads towards the southern extremity and the prospects for finding even more sharp, muddy crawling are excellent.

 

[Roger W]

I suppose while you were experiencing those 17 hours of agony you could always console yourself with the thought that you were exercising in the open air. 

I'd better get my coat.

 

[mikem]

Not sure they worried about that 30 years ago!

 

[tim.rose2]

I've always liked the idea of saying I've been to the end of Ammonite passage but can think of other places I'd much rather spend 8 hours underground.  A trip with Mike R & Mike K was discussed a few months back but my contribution toward the enthusiasm was along the lines of "I'll follow and turn back when I've had enough".

Streams on Portland - The one from Culverwell is the only surface stream on top the island.  Tumbles over the cliff at this 'impressive' waterfall...

There are a few underground streams which emerge on the cliffs, the best known are at Church Ope and Freshwater Bay.  The one at Freshwater Bay was used as water source for the Naval base in Victorian times.  A shaft and pumping station lies in the grounds of Cheyne House.  A short mined tunnel (locally known as either Red Door Tunnel or Smugglers Cave depending upon who you ask) leads to the base of the shaft:

I've always been convinced there's some cave under this part of Portland to find, perhaps even active streamway as the flow never really dries up in the summer and can be quite substantial in the winter.

 

[Ed W]

There's lots of other man made underground stuff on the island too...

 

[Pipster]

Great presentation Tim! Very interesting; thank you.