[Nmap] Northern Glide Cracks

[Christoph Dietzfelbinger]

A few days ago I dug a pit at timberline (1470 m) on the Solitaire 
Meadows in the Howsons. HS was 260 and the lower 130 cm were moist to 
wet. The ground was entirely wet. There had been numerous glide releases 
on the smooth rock slabs across from the lodge, probably during the last 
warm spell. I also checked the small creek behind the lodge. It was 
flowing freely and much of it was open like the other creeks. So Sean's 
theory makes sense to me. It has not been cold for long; the ground was 
saturated; the lower half of the snowpack is moist; it's insulated by a 
good metre of low density snow. There can be a lot of water available 
for lubrication at the ground in these conditions, and voila the famous 
glide cracks along Highway 37.

Christoph Dietzfelbinger
IFMGA/ UIAGM Mountain Guide - Bear Mountaineering and the Burnie Glacier Chalet
Box 4222	Smithers, B.C.		V0J 2N0	Canada
tel. 250-847-3351/ fax 250-847-2854 
info at bearmountaineering.ca		www.bearmountaineering.ca



sean fraser wrote:
> Hi Folks...so some of you may be looking at the recent LFH and NW MOT 
> posts on  the infoex regarding Glide Crack failures during -25 in Dec, 
> and think we are on crack. Well, after 3 years of seeing this in the 
> Ningunsaw area, this year is definetly the worse, and I am interested 
> to hear anyones thoughts on this. IT is widespread at TL and BTL, all 
> aspects from Treaty Ck in the W, to well up the Bell Irving River in 
> the E. Some BTL terrain actually looks like a crevasse field, and 
> there are some real hazards with skiing into these over a blind roll. 
> These things seem to be moving more on low angle terrain, even as low 
> as 15deg.
> Had a chat with Dr. Jamieson the other night, here is my theory, 
> wondering what others have experienced.
> So, I believe with a certain smooth wet soil type, such as heather 
> moss/clay, which I hear is notorious up this way for poor soil 
> stability snow aside, That with heavy precip in the form of rain 
> before winter the earth is super saturated. Then, copious amounts of 
> moist/wet snowfall insulate this layer, and above normal amts of HN 
> fall, and things start to glide. Early Nov rain at low elevation 
> probably does not help. The localized glides start to open, and glide 
> creep. Then with a sudden, intense blast of arctic air, they become 
> brittle, much like a cornice, or icefall and collapse/fail. The 
> resulting slab often only involves the area of glide, and does not 
> propogate over wide areas.
> I dug a 320cm full profile to ground in the Bell Irving the other day, 
> and was able to squeeze half a cup of water out of a handfull of 
> dirt/moss.
> Last year this same sort of thing occurred, except it was almost a 
> full month earlier, as the cold snap was in November. Glides failed, 
> but not as widespread as this.
>  
> Anyways, just curious what others in the area have seen past or 
> present, and if they feel this is localized phenomena for the type of 
> soils for the area. I have seen many glide cracks in spring on wet 
> lubricated rock slabs, that looked much riper for failure than these, 
> and even coaxing them with copious amounts of An/Fo  for several days 
> fails to release them.
>  
> Have a good holiday season folks, hope your fire is a burning!
>  
> Cheers;
> sean
>
> */Sean Fraser/*
> ACMG Ski Guide
> CAA Professional Member/ Avalanche Consultant
> Smithers, BC
> 250-847-5537
>
>
>
>
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