Congratulations All! To the best of my knowledge there are no other caves in the UK that manage to combine both water-worn passages and mass-movement rifts on anything like this scale, if at all; and this growing system is quite something! Looking at your outline survey, there are still...

I don't know the area and consensus strongly suggests a collapsed denehole. If though it is natural, Graigwen points to a possible cause - the chalk. This is subject to dissolution forming "pipes" - roughly vertical shafts usually tapering downwards; into which overlying sediments can...

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...

Thirty-year span of observations... So, I wonder if it's not so much that bats are becoming used to cavers, but are cavers generally more aware of not disturbing them than we might have been in the past. It's ever so illegal for us to touch the animals without proper licence etc. etc., but...

Upwey Wishing Well is on the base of the Portland Stone, and becomes discoloured in high flows by the underlying clay. The geology of Upwey is much the same as on Portland as the site is on the North limb of an unsymmetrical anticline, deeply eroded to produce the Weymouth Lowland; but the...

I think the pictures showing the airy nature of the roof speak for the past digging attempts not making much progress... including my own team's in the '80s. One thing we did was start to clear the floor to solid, to make the passage nice and roomy, then on the next session we found someone had...

Warning above duly noted... And I have only just spotted the thread! The Wessex book is now on the MCRA, though not yet with its surveys and other diagrams. it's a bit awkward to read as it is one enormous 'Word' file so the pagination goes all wonky, but at least it's there. The surveys are...

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...

Indeed - Tim passed me the link to this! The rather remote location (for Portland), and the world's oceans, may well be why this is a new find. I have sent a message to Mike Read, with a copy of the link, to see if he knows anything about it, but I don't recall him ever telling me of caves like...

I reconnoitred the Inmosthay Quarries, roughly in the middle of Portland, recently. (There is a rather ill-defined right-of-way I THINK across the area from Wide Street to Easton Lane; other parts were visible from the surrounding land). Nothing of any speleological interest left. The whole...

On "decent drill bits" you can re-sharpen tungsten-carbide tips but need a silicon carbide ("green grit") wheel and preferably on a grinder fitted with a jig to ensure correct angles and symmetry. I have helped large masonry drills by pilot-drilling but I agree with JohnMCooper that it's not...

The physics that make the Ireby Pump such hard work is more than the mere weight of water. It's also atmospheric pressure opposing the piston as drawing it up produces a partial vacuum below it. Add to that the suction head (10m depth = 1Bar). When Pete Hann & I built an Ireby Pump, using...

The law has long been very clear on the nature of a public footpath. A lawyer would know better than I but long before CROW was a gleam in a politician's ink-well, it is strictly a pedestrian right-of-way from one place to another, and in theory, unless the law has changed, or the land flanking...

No not really but I certainly advocate surface practice in specific techniques like SRT & - come to that- ladders & lifelines. Maybe I'm spoilt but I have the advantage of having received considerable training & support (including surface sessions) from fellow club-members over many years and...

I can't view the videa either but that may be the way my own 'confuser' is set up... The "rice on speed" are spring-tails (Collembola sp) but I don't enough cave-biology to identify the species. They are primitive, wingless aquatic or semi-aquatic insects that I think browse on bacterial...

This is a question oft upon which have I pondered, ever since seeing a snoozing bat near the White Cliffs in Agen Allweld. I wonder if the bat Passage animals had found a way in through one of the old mine shafts in the vicinity. I don't know of any mine working breaking into GB but one...

Just to make things even more fun, chert can also form sheets, filling bedding-planes or joints over large areas. There are fine examples of this puzzle in the Upper Jurassic limestone of Portland. It may not require much change in sedimentation to produce a bedding-plane in otherwise...

Re Gus Horsely's statement of the effect of an impermeable formation (an aquiclude). In some situations it can also confine water below it. The eample I know particularly but I am sure is not unique, is that of the phreatic phase of the long-fossil Blacknor Hole, on Portland. There,  a chert...

It's a thought, as I've always been led to believe the air temperature in caves and mines is fairly stable around their localities' mean annual temperature, or at least does not vary as rapidly as that outside. The first port of call would be a comparative study in a selection of sites in...

First: Thankyou for the information from the divers - a very interesting field! Secondly, a CORRECTION - of my own clanger! I'm suprised no-one else spotted it. In the paragraph about bats I gave the reference SPL for air acoustics as 0dB re 26?Pa. it should of course be 20?Pa. I'd recalled and...