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Avalanche vs Crevasses


salbrecher

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How deep is the snowpack? Winter/spring snow is often so deep the crevasses are something its not worth worrying about.The small ones get filled in and the big ones bridge over with a 9 foot thick bridge. From about March thru early June the rope is OFTEN (but not always) dead weight in your pack.

Also, in winter, the glaciers at lower elevations do not advance as rapidly (colder), so crevasses tend to close up some, and get narrower. Then they widen up in summer.*

* I just know some real glaciologist type like fern is gonna challenge me on this one so I confess in advance I probably made this "fact" up. It sure sounds plausible though!

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This has remained a burning question in my mind, whether the ski mountaineer assumes a higher level of risk if he/she does not rope up on a glacier. I've never been on a glacier with skis on. I can imagine wearing a rope to ski up, but what about skiing down? Seems pretty impractical to rope yourself to someone else unless your group is mighty well coordinated and skis at exactly the same speed. So if you're not going to rope up on the descent, why bother roping up on the ascent? Yet clearly this violates the cardinal rule "never go onto a glacier unroped." What do the veterans among you have to say?

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Skis transfer your weight out over a larger surface area making it much less likely that you'll punch through. Skis are also capable of bridging smaller crevasses. Roping up on the way up allows you find hazards and mark them for the ski down. If a route is so open that I feel the need for a rope on the way down, I'll likely just bail for the comfort of a cold beer in a warm bar.

I also wouldn't say that one should never go onto a glacier unroped. It's a matter of comfort level, knowledge of the area, and current conditions.

On a similar note I was up on Silver Star last week and there are a couple of rather large crevasses below the headwall, which have been all but non existent in the past. I'd bet my last beer they will still be open when the highway does this spring.

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I'm not sure which post on glacier travel to respond to; so I'll respond to this one.

I've been unroped on a bunch of glaciers. I've skied on quite a number and I've never roped up while skiing.

Skiing on glaciers in the early spring seems safe to me. Big snow pack covers most crevases, and you can avoid the ones it doesn't. Also skiing with a rope really really sucks, or at least it must since I've never done it.

As far as climbing unroped on a glacier. I've made judgement calls. After climbing on big glaciers in Alaska and glaciers in the Canadian Rockies, I'm not so worried about glaciers in the cascades. However I would not encourage anyone to do this, and I think you should have a lot of experience on glaciers in the area you are climbing in before you do anything rash.

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  • 1 month later...

Originally posted by Dru:

quote:

Also, in winter, the glaciers at lower elevations do not advance as rapidly (colder), so crevasses tend to close up some, and get narrower. Then they widen up in summer.*

* I just know some real glaciologist type like fern is gonna challenge me on this one so I confess in advance I probably made this "fact" up. It sure sounds plausible though!

The ice flows when the ice/snowpack is ~70' deep because the pressure causes the ice to become plastic (i.e., malleable, fluid) and therefore flows downhill. Even though it is still technically a solid, the extreme pressure gives the ice different mechanical properties than we can experience in "normal" (read, survivable) conditions. So temperature only affects the ice at the surface, and as long as it stays below freezing, it will have no net effect on the rate of advancement. Now the weight of the amassing snowpack, on the other hand...

[ 03-22-2002: Message edited by: joekania ]

[ 03-22-2002: Message edited by: joekania ]

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I've done a bit of glacier study also and have no indication that crevasses are narrower in winter - just covered over. As you know, the term we hear in early summer "crevasses are opening up" is technically misleading, but who cares - we know what it means.

Surprised to hear about cracks on Silver Star Glacier - I thought it was stagnant. Was surprised at the number of significant cracks on Ruth Mtn last September too. I know its a popular teleski in early summer, probably okay, but there are cracks. [big Drink]

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