Rock fall off p2 City Park

[j_b]

good point. Natural glaciers are good at removing the loose ones. I assumed that the most of the lower town wall was glacier carved also.

 

And you were probably right, although there was much more ice flowing down Howe Sound than down the Sky (to 1st order, glacial erosion scales with sliding ice flux). Howe Sound was likely glaciated more recently as well.

[Buckaroo]

Go there and look at it Dru, I did.

 

a rectangular block 60" tall and 18" wide would have to be moved 18" at the top for it to tip. This would be less if it was hanging off 2" already but no way it's 1".

 

""dirt, water, and vegetation""

 

there was no vegetation, the dirt was at the bottom of the crack. Water and dirt can move rock if that's what it's resting on, that's not the case here. The only natural possibilities are frost wedging and rock fall from above. Frost wedging isn't likely due to the shape/measurements of the ledge and block. Rock fall from above is unlikely due to quantity of fresh debris at the bottom.

 

 

[billcoe]

OMG, a block fell off at Index. OMFG!!!! The sky is falling the sky is falling. A block fell, it must be the republicans!!!!!!

 

Get a grip dude. Take it off the internet.

[Buckaroo]

OMG, a block fell off at Index. OMFG!!!! The sky is falling the sky is falling. A block fell, it must be the republicans!!!!!!

 

Get a grip dude. Take it off the internet.

 

A block didn't "fall" off it was trundled to make a route "safer". Not because it was a hazard to those below but because you could fall onto it. So billcoe, why don't you join up with these guys and destroy all the ledges at Index to make it "safe" for the gumbies. Where does it stop is my question? If people were grid bolting or hold chipping on the LTW people would be up in arms. This is worse.

[Off_White]

Terrorist strike by the Columbia Gorge Choss Crew?

 

Naw, I don't think so, but those guys are some busy busy beavers!

[billcoe]

LOL!

 

I think it's something you local dudes need to be discussing. It could be it was discussed and you missed it. I'm not commenting on a block I've never seen in person. Could be dangerous and a killer. Maybe not. Maybe it fell off via rockfall smacking it, maybe not. Who can say. A head sized falling from the rim could generate tremendous power and velocity. Looks too beefy/weighty/heavy for a person to move.

 

Somethings should be discussed in person, this is one of them IMO. Besides, it was Obama and his crew who probably pushed it off.

[j_b]

A block didn't "fall" off it was trundled to make a route "safer".

 

I don't think you can exclude that the block was wedged off its base by frost over time. The post-rockfall pic posted by someone on page one of this thread shows that the base of the block wasn't rectangular (considerably thinner at its western end) and there was probably already a great amount of dirt accumulated at the bottom of the crack. The dirt mixed in with rock debris could have provided a good porous medium for frost wedging to occur and could have raveled further down the crack when melting, thereby preventing the block from settling back into its unwedged state. [/armchair hand waving]

[G-spotter]

I doubt you need frost, besides it wasn't cold enough for that to be the primary mechanism although it likely produced widening over time. Wind, together with water acting on dirt and vegetation inside the crack, are sufficient.

[billcoe]

I'm with jb and Drew, the dirt underneath in that picture might mean it wasn't sitting flat on a flat ledge at all like the front would suggest.

 

Anyway, I've of the opinion that if you can just so easily grab any block which is on a route and yank it off, then do it and do it in a safe controlled manner at a time of YOUR choice so as to avoid the uncontrolled and random killer fall. If it rocks forward when you grab it and you think "man, that's going to roll off of there and kill someone", and then just leave it, that's baloney in my opinion.

 

We have done controlled drops at Beacon collaborating with the railroad and the park rangers to set up the optimum time, and it's the best-safest way for all concerned. These are basically things which are visibly tottering time bombs though, that often build up and get loosened over the winter to spring when no one is climbing there and will fall off on their own at some point.

 

Joseph had some great organizational work last time which I could detail further, setting it up both so that the concerned authorities/stakeholders were involved and present to co-ordinate and some amazingly professional pre-trip tactical climber organization with pictures that had arrows and diagrams so we attacked it with multiple parties in contact with each other attacking specific problem boulders at separate locations with ground spotters in safe areas.

 

It doesn't stop all natural rock fall onto the RR tracks or protect all climbers in all situations, but it sure as hell helps both the Railroad and the climbers. If you can easily pull it off then you should do so, the one thing I've learn is that you often cannot determine what will pull easy or not. Even stuff that is rock solid for years can become loose.

 

Can't say what the case was here.

[j_b]

many things could have provided a small trigger once the block was wedged far enough from the wall. You are likely right that water, veg and dirt is all that could be needed, but I'd guess that Index has the right climate during winter for lots of temperature cycling events about the freezing point.

[rob]

A block didn't "fall" off it was trundled to make a route "safer". Not because it was a hazard to those below but because you could fall onto it.

 

 

Oh, so now not only do you know it was trundled, but you know exactly WHY it was trundled?

[Buckaroo]

the base of the block wasn't rectangular (considerably thinner at its western end) and there was probably already a great amount of dirt accumulated at the bottom of the crack. The dirt mixed in with rock debris could have provided a good porous medium for frost wedging to occur and could have raveled further down the crack when melting, thereby preventing the block from settling back into its unwedged state. [/armchair hand waving]

 

So the close end is about 20" wide and the back end is about 10". All my theories still hold true. The block is frost wedged out about 1" to 2". The base is flat, the block is vertical, the wall is vertical. Average 10" and 20" is 15", the block would have to frost wedge out 5.5" to 6.5". That's just not happening since the photo was taken.

[stevetimetravlr]

My thoughts are that there is a good chance that the block was frost wedged off. Thru time, the frost lifted the block and evertime it melted, more and more dirt was put under the block lifting it until finally it may have pulled off in some ones hands or by itself. The photo seems to show that. If the block was taken off with a hydraulic jack, that is super uncool obviously.

 

[Nitrox]

Anyone check to see if Chuck Norris was in the area?

 

 

[Buckaroo]

I'm going to investigate further for all you naysayers.

 

My brief examination, 30 years of engineering background, and talking to the regulars says this block was trundled.

 

Frost wedging or rock fall from above is the only thing that naturally moves a 4.25 ton block that's sitting on a flat rock ledge.

 

Frost wedging and rock fall from above is ruled out from my cursory exam. I'll take a closer look to solidify my hypotheses.

[Buckaroo]

the rock scar on the flat ledge is clean, the dirt was in the crack at the back of the block and it fell onto the ledge when the block was vacated.

 

""If the block was taken off with a hydraulic jack, that is super uncool obviously.""

 

THANK YOU FOR SAYING THAT.

 

No other fellow CC'rs seem to be at all concerned about this

 

We're in the middle of the delicate process trying to turn this place into a protected park and some misguided people are throwing off 4.25 ton blocks onto the trail below.

[Buckaroo]

A block didn't "fall" off it was trundled to make a route "safer". Not because it was a hazard to those below but because you could fall onto it.

 

 

Oh, so now not only do you know it was trundled, but you know exactly WHY it was trundled?

 

I know nothing exactly, this is all theory based on observation up to this point. I'm just going to have to look closer to prove or disprove my points.

 

So Rob, if it was trundled why do you think it was trundled? Meth heads on a lark? Or climbers trying to make the place "safer"?

 

I suppose someone un-educated enough to think tossing a 4 ton block is ok would be un-educated enough to think this was a hazard to those below. And if they did it to make it a clean fall for the next pitch then they are just weak gumbies who shouldn't be on the pitch in the first place.

[dberdinka]

Sol was on TC or GD several years back when a large corner maybe 100' to the right exploded down onto the trail. You have to scramble over a big block now just before you get to the wall. That occured shortly after some very significant rainfall, maybe hydraulic pressure?

 

The flake on PA jumped off unassisted with witnesses on the ground.

 

Also recall a guy taking a block to the chest at the base of the LTC and being helivac'd out. Came out of know where.

 

Anyway, spontaneous rockfall does occur, at Index more than elsewhere it seems.

 

 

[tvashtarkatena]

Terrorist strike by the Columbia Gorge Choss Crew?

 

Naw, I don't think so, but those guys are some busy busy beavers!

 

What have I been sayin? BORDER FENCE.

[tvashtarkatena]

We've got that river but these illegals seem to be able to swim it. That, and the legally sticky fact that half of em live in on our side.

Edited May 10, 2010 by tvashtarkatena

[Good2Go]

I don't have a lifetime of engineering under my belt, but I saw the "new" ledge yesterday and there were some obviously new chips at the edge, which appeared to me to be the product of an impact. I'm also a believer that the most likely cause should be entirely ruled out before latching on to the fanciful.

[Buckaroo]

Don't disagree with you, spontaneous rockfall does occur.

 

but there's also a lot of "cleaning" some of which is justified and some of which is not.

 

The block on PA was a propagation crack that finally went all the way through from the weight. It was an attached block not on any ledge.

 

This was a detached 4 ton flat bottomed block sitting on a flat ledge.

 

M.M. an old climbing partner of mine was under PA when the block fell. He heard the noise and they dodged out of the way, it chopped their rope into several pieces.

[tvashtarkatena]

 

No other fellow CC'rs seem to be at all concerned about this

 

We're in the middle of the delicate process trying to turn this place into a protected park and some misguided people are fantasizing and posting incessantly about some illusive and wanton spirit throwing off 4.25 ton blocks onto the trail below.

 

 

[tvashtarkatena]

I'm going to investigate further for all you naysayers.

 

My brief examination, 30 years of engineering background, and talking to the regulars says this block was trundled.

 

Frost wedging or rock fall from above is the only thing that naturally moves a 4.25 ton block that's sitting on a flat rock ledge.

 

 

 

Frost wedging and rock fall from above is ruled out from my cursory exam. I'll take a closer look to solidify my hypotheses.

 

You forgot earthquake. Problem solved.

[Buckaroo]

I don't have a lifetime of engineering under my belt, but I saw the "new" ledge yesterday and there were some obviously new chips at the edge, which appeared to me to be the product of an impact. I'm also a believer that the most likely cause should be entirely ruled out before latching on to the fanciful.

 

If it was pushed off it would damage the edge as it tipped over. As it's pushed to the edge more of the weight is concentrated on a smaller area at the edge.

 

from my investigation trundling IS the most likely cause. Frost wedging, rock fall from above or "osmosis" from vegetation, dirt, and water are less likely.