Jump to content
  • Announcements

    • olyclimber

      WELCOME TO THE CASCADECLIMBERS.COM FORUMS   02/03/18

      We have upgraded to new forum software as of late last year, and it makes everything here so much better!  It is now much easier to do pretty much anything, including write Trip Reports, sell gear, schedule climbing related events, and more. There is a new reputation system that allows for positive contributors to be recognized,  it is possible to tag content with identifiers, drag and drop in images, and it is much easier to embed multimedia content from Youtube, Vimeo, and more.  In all, the site is much more user friendly, bug free, and feature rich!   Whether you're a new user or a grizzled cascadeclimbers.com veteran, we think you'll love the new forums. Enjoy!
Sign in to follow this  
Wildearth

Ice density in crevasses on the Coleman Glacier

Recommended Posts

Hi I rapped down into a crevasse on the Coleman Glacier, day before yesterday and encountered near  impenetrable ice.

Do let me know your opinion on :

  1. Does the density of ice vary in crevasses on the Coleman Glacier? ( A glaciologist I spoke with said it does, but there is no pattern. The deeper the crevasse, the denser the ice, lower down because of flow pressure, but there are many other factors...etc
  2. Do monopoints work better on bulletproof  crevasse ice? (I was wearing brand new Grivel G12's and they were barely making a dent!)

I haven't found any answers on  crevasse ice density despite scouring the web and asking amongst  my ice climbing friends. 

Many thanks !

Share this post


Link to post
Share on other sites

Monopoints may be the ticket, but I suspect that vertically oriented frontpoints on something like the G14 would also work well.  Most importantly with any crampons, they need to be sharp!

And yes, my experience is that the deeper you go the harder the ice, but your glaciologist would know better.

Share this post


Link to post
Share on other sites

The role of pressure is to remove the air. Once the air pockets are gone, the ice is solid, then the pressure has essentially no impact on density. 

It should be the same as glaze ice that forms over rock without any air bubbles. Ditto for "black ice" on roads--all will have the same density. But the hardness also depends on temperature, with the colder ice being harder. 

 

Share this post


Link to post
Share on other sites

I would guess (not being an ice climber), that the perception of hardness might also depend on the rugosity (i.e., bumpiness). The fairly flat ice walls of a crevasse would then seem harder to penetrate even if the inherent hardness was the same as a solid piece of ice with corrugations from drips because you could aim your pick between corrugations and get it to stick better. 

Share this post


Link to post
Share on other sites

Thanks G-spotter for those links. 

I didn't see anything about the higher-pressure ice deforming less or limiting crevasse depth, but it sounds interesting. I'll look into more later. 

In my limited reading of ice, I don't recall any definition of "hardness", but I once learned that the grain structure affects the flow properties. Who knows though how any of that related to the guy swinging his pick.

I'm not even sure what I said about hardness depending on temperature is right, but there is the interesting phenomenon of regulation, where one can (very) slowly pass a wire through ice at temperatures near the melting point. It is not pressure-melting. It does suggest a "softness" of sorts.  

Ice is a fascinating material. 

Edited by JonNelson

Share this post


Link to post
Share on other sites

well, it goes from brittle to ductile at a depth of ~50m. you need 50m of ice thickness to flow, and so most crevasses are 50m or less deep because that's the brittle fracture depth.

i don' t think that's what the OP observed though.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

×