UKH

The rate of widening of the crack on the upper left side of the North Crag continues to accelerate and the usual warning to avoid the North Crag remains. There is now a permanent monitoring station on the crack, should give useful data but probably won't predict date and time of collapse. There is some additional information at www.frcc.co.uk.

Good overhead shot from Dom Bush here;

https://www.instagram.com/p/BmGmGcHD9ua/

Blimey!  Great (and terrifying) shot.

So, what's the recommended hard rock tick once North Crag Eliminate goes? 

Much like Totalitarian is in for Deer Bield buttress.

Just re read "God's and Gremlins" an article in Climb magazine 2006. Where Mick Lovatt, Tim Whiteley, and Steve Wilcock climb the "new" Deer Bield Crack.

I wonder if it's had a second ascent?

Still a few ticks in the log books for this year.

I think Dom's photo might change peoples minds now.

Despite there being yet-to-be discovered Amazonian tribes that know about this, it's still getting logbook ticks!

And very clear BMC signs at the crag if I remember correctly.

Each to their own, but you'd have to REALLY want that tick eh?! 

Maybe it's a competition to be "last ascensionist"?

North Crag Eliminated...?

Let’s hope it lands in the right place at the right angle to get some decent bouldering 

The Rock is pretty good up there but I don’t think it’ll end up in one piece!!

To be fair, the chances of it going when you're on it are extremely low. A lot more dangerous to walk through a forest on a windy day, and I don't think many specifically avoid doing this.

Are you sure about that? I haven't climbed the route in question, but doesn't it involve using the crack that is the active fissure? So in this case the climber could be the trigger event. You might think a 70kg climber doesn't make much difference to a 100 ton (?) block, but something is going to end up being the trigger event.  (I think something like this happened on Scafell Central Buttress route?)

I always found stepping off the remnants of that tree the most worrying part of NCE!

North Crag Eliminate is one of the ones I haven't done there (I think - there are quite a few 'Eliminate'-type route names there!). It was more a general comment about climbing on that buttress, but yes, a climber is going to make zero difference as a trigger. I would expect likely triggers (other than gravity) to include things like frost shattering, minor earthquake tremors etc.

Hmmm, not sure about zero difference. 

Whoa! That's made the point, eek......

Perhaps a similar level of difference as a fly landing on a table would make to the stability of the table. 

Earthquake or progressive gravitational collapse will do it if it wants to fail. No frost action, the crack is dry and too low to be affected by frost action.

DC

A table whose legs are eaten away by woodworm to the point of collapse? 

Looks big enough to get some car jacks in there! Someone get to it, it'll be one hell of a trundle!

Thankfully I did the Overhanging Bastard as a youth.

hope the auto-monitoring includes some sort of trailcam to record the event (as well as thugs with jacks)

Won't there come a point when it will have to be done in a controlled way (e.g. with explosives) to avoid injury? I.e. everyone cleared from the area first.

I'm slightly suprised that it's not considerred we've reached that point.

You keen?

I would worry a great deal about the buildings and houses down below. It's hard to work out the trajectory by the naked eye but if I lived or worked in those building I'd probably feel quite uneasy just now.

I've recently had an email from someone who knows their stuff - their estimation was that there is 1500 tons of rock waiting to peel off. I reckon that could go quite a long way when it hits the floor and breaks up.

It's a very reasonable point but having once missed my date with 'geological time' (and c15,000 Ton of crag) by no more than a few hours I'd not choose to knowingly take the chance again for a tick in a book.

I wonder where it'll stop when it finally drops, it's steep most of the way to the road if my very old memory serves.

jk

I should add, that I'm sure far more scientific evaluations have been done on the risks to those buildings than my general observations.

They might be totally out of the fall out zone, they just look kinda vulnerable to me.

Which isn't much unless you've balanced the table on a knife-edge.

Something will trigger that collapse. Sure it's likely to be frost or soil shrinkage, water or wind-load but there is absolutely no reason it has to be.

jk

Frost is not a factor, nor is soil shrinkage - the greatest movement each year is between end-September and end-November. The crack is dry - water is not a factor.

DC

The biggest internal temperture drop?

Interesting. Any theories what drives the accelerated autumn movement? Dry with low sun and cool air could heat cycle it it more than other seasons? Or something to do with vegetation drawing fluid back from the leaves into the woody bits maybe?

jk

The only logical reason is thermal shrinkage, but that is only a perturbation on top of the main process.

DC

Won't thermal shrinkage/expansion be the main process? I'm imagining that thermal shrinkage/expansion generates movement and gravity ensures that the net direction of the movement is downhill...

Lots of rain in cumbria in late autumn?

I suspect you're right Michael.

I'm maybe just a bit over-cautious after spotting this video on FB recently, suggesting that little ol' climbers can potentially have quite a big impact: https://www.facebook.com/EmissionLaPlaceDuVillage/videos/468728740290871/?p...

I never quite managed the last 10 feet but I don't need it enough to go back for it now...

Groundwater levels are usually at their lowest around late autumn. This may sound weird but it has a lot to do with the uptake of water from vegetation along with evaporation caused by the power of the sun and wind. This means that until vegetation fully dies back not much water makes it down to the water table.

As the water table is likely to be at it's lowest around now this might indicate that shrinkage may be a factor.

And rainwater running down behind and lubricating what ever the block is resting on?

The crack is dry. There is no seepage in the area of the mobile rock. AJM is correct that the cragtop area is presently relatively dry due to a dry-ish summer until August. However, we are talking about a 200+ foot crag here, it is all mostly well above the local water table and the soil cover at the crag top is relatively thin.

The underlying process that is opening the crack is related mostly to localised tectonics, it started after the Coniston earthquake Dec 21st 2010.

DC

Looking at the map it looks like it threatens the houses. Is this the case.

I don't know enough about the underlying soils or geology and it's very interesting that tectonic activity has started the movement, however if there is noticeably more movement in the period between Sept and Nov every year then that would imply that processes other than local tectonics might be at work as well.

As for the height it would be worth noting that skyscrapers have been threatened by the drying out of water tables due to human extraction, so a small shrinkage in deep underlying clays or rocks may actually have a large impact on an already weakened fracture line.

It's a very interesting subject, I'm definitely going to head of and find out more about it.

Yes. The buildings could be threatened if a boulder was able to roll a distance as has happened in the Alps periodically. There is an 80-90 metre drop vertically and 200 metres horizontally to the first building below the crag.

Edit: There are quite a lot of trees in the way.

DC

I remember I put my leg down a deep crack in the crag top when I did NCE in 1977 .

I'm fairly certain the crack will be full of jammed chockstones partway up. As things expand/contract/move the 'flake' will move outwards and the chockstones will move downwards preventing things from returning to their previous state. As such, the crack will inexorably widen until the 'flake' falls off or the chockstones reach the bottom of the crack (which is highly unlikely).

Is there a reason why the 'flake' hasn't simply been geo-tethered to the cliff with steel cables like has been done at the top of the via ferrata above Arco?

Before I start, let me point out that I make this statement with no knowledge whatsoever about what I'm going to say.  However, such things never stopped me before, so . . .

If a large boulder falls from the top of the crag because, well, entropy increases and bits of that boulder hit, injure or kill someone and hit, damage or destroy property, then that's somewhere on a spectrum from unfortunate to tragic; but it's what insurers would call an act of god, it's no-one's fault.  However, if attempts have been made to prevent such a thing occuring and it happens anyway, can the body whose actions failed to restrain the boulder be held liable?

T.

Obviously all your fault then!

1500 tons if this drops and breaks up perhaps it will provide some boulders for the boys and girls (and those in between) who like that kind of thing to play around upon. Just trying to inject a bit of optimism but I,ve missed out on NCE but done most of the others within my ability.

But the crack is completely open to the elements, as can be seen in the overhead photo. So when it rains, the crack is wet, a lot wetter than it would be by seepage alone. If there's a frost that night... 

A few sticks of gelignite would most likely sort it out.

That would be North Crag Eliminated.

They started fracking in Lancashire yesterday after causing an earth tremor several years ago. So maybe this might this might move it ! As I recall years ago an earth tremor in South Scotland triggered the rockfall at raven crag walthwaite.

Walthwaite collapse was winter 2006-2007 possibly assisted by tree roots. I haven't found an earthquake on the BGS database to correlate that event with. However, the whole Langdale Coniston Dunmail Thirlmere fault line has been repeatedly active for centuries. It is regularly active now. It is also worth pointing out that the greater Morecambe Bay area is tectonically very active and has been since it went up 7-10,000 feet in the Tertiary. Hence vertical beds in places. It is quite possible, in fact probably highly likely that the Cuadrilla frack-induced earthquake had a natural component anyway, or indeed was a wholly natural event. Obviously coincidences are unfortunate. Fracking is done only within shales deeper than 1000 metres from surface so any impact is usually extremely local, whereas the Lancashire area bounding Morecambe Bay has some huge faults that regularly move.

So far as Castle Rock is concerned, another significant movement on the Coniston fault will obviously contribute to the eventual collapse. No one knows when however.

Even in rain the crack stays fairly dry, obviously a little rain will penetrate but very little. Nothing significant drains into it. Frost shattering does not begin on the Helvellyn range until an altitude of 2000-2500 ft is reached.

DC

That should be wide enough to comfortably chimney up soon!

Is there a reason that there's no move to pre-empt it's demise under controlled circumstances? Is it perhaps considered to not present too much of a risk to life and limb and property?

There would likely be unintended consequences. The perpetrators could become legally liable.
As a friend of mine said, "if you f___ with nature, nature will f___ you".

It may never fail (unlikely in my view), but if it does, the repercussions below could be significant, it is unpredictable.

DC

No I didn't mean clandestinely, I meant officially.

I am sorry to tell you that you are off by a factor of more than 5,000. An average dining table weighs about 100 kilos, and 1 fly weighs 15 mg - so there are 66,667 flies per kilo, and therefore 6,666,700 flies weigh the same as the average dining table: whereas 1,296 (70-kilo) climbers weigh the same as a 100-ton block

So did I.

DC

You could factor in that climbers have camming devices ( 1/tan -1 13.75, c 4) and fall off occasionally ( about ten times body weight on a very harsh fall ).

Yes, thanks, that's helpful, but I'm just comparing weights for now

Just wanted to point out the extra forces involved

At castle I used to avoid a flake on the first pitch of triermain eliminate, using it with trepidation and occasionally a sling runner.

One day at the crag someone put a cam behind it , we watched with added interest.

I finally got round to using a jemmy bar to test the flake, I gave up when it just flexed and sprung back. Amazing how flexible it was, might just be the rock type.

But the estimate above (Dom Bush) was 1500 tons, not 100. 

Can you explain this - I thought frost shattering may occur whenever water freezes? Plenty cold nights and even days at valley level in the Lakes during the winter. 

Indeed, my water pipe and my Mother's water pipes both froze last winter and burst the external pipes. However, those are closed systems. My point was, if you go and look at the fabric of the rock in the outdoors, you can see where frost action has shattered rocks and where it hasn't, so I was just relating my perception that I have only seen frost shattered rock high up as described. Certainly frost will have no discernible effect on the crack at Castle Rock.

DC

I agree it's unlikely to have a great influence. It would only be thin cracks where a breadth of the crack may fill entirely with water, and therefore ice.

OK, and thanks for that - I was going with bigbobbyking's estimate of 10 October

"You might think a 70kg climber doesn't make much difference to a 100 ton (?) block"

I think this was a number plucked from thin air, not a considered estimate.

aye, well, we all know the main influence is gravity

it's not possible to know for certain how much of whatever influence is attributable to the whole , there could be fissures within the main rockmass leading seepage to the base of the crack...... and frost action happens wherever there is frost. just like you see frost-heave in soil, the expansion will create some outward pressure and more so if its confined.

anyway:

for that rock I'd take 2.8t/m3 - anyone got a decent handle on the dimensions: h/w/d?

You're right - I've no good feeling of how heavy big blocks of rock are...

Also I think profitofdoom's estimate of a typical table being 100kgs is a bit over egged too. So if we say rock 10x heavier, table 10x lighter: Fly to table ratio still 50x smaller than climber to rock.

Bloody hell. Where do you buy your dining tables from?

Estimated 50 x 40 x 10 feet, that is:

15 x 12 x 3 metres, that is 566 m3

566 x 2.8 = 1580 tonnes.

DC

I think that includes the food on it.

But what if the rock lands on a conveyor belt ?

OK, and sorry about that if so

OK overegged (although it was averaged from several Internet sites giving dining table weights), sorry.... but "table 10x lighter"? Then it would only weigh 10 kilos!

Errrr the dining table weight was averaged from several Internet sites giving dining table weights