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Snow Holeing

Published on 25-06-2012 16:11

18 Comments

Snow-Holeing
by Neil Foote

Be it necessity or leisure, the snow hole is the most effective form of shelter within a winter mountain environment. Yet unlike woodland shelter, there has to be a lot more judgment and understanding of the building medium and topographical features to avoid an unpleasant, potentially dangerous experience. The snow hole has been essential to survival for many over the years - from indigenous communities; the famous Heroes of Telemark (who led a resistance against Nazi Germany in Norway); to present-day Alpine and Himalayan climbers.

The first thing to think about is location. Prevailing winds are typically South West in this country, causing wind-carried snow to lay deepest in the North East Lee slopes (this of course depends on the history of recent wind conditions). In Scotland, especially in the 2010/2011 season, the snow can lie for up to 10 metres deep, which is ideal for excavating a snow hole.

An avalanche probe should be utilised to test for any discrepancies within the snow pack, feeling for any excessively hard snow with wind slab (hard packed freshly blown snow) lying on top. An avalanche pit is also a useful tool to get an idea of the local stability within the different layers in the snow. A hidden layer of Graupel under slab can act as lubrication for any subsequent snow fall. Being avalanched whilst digging, or worse being buried whilst inside a snow hole is a real possibility.

Figure 1. A typical Lee slope with good snow build up
Choice of Snow Hole

Temperature will dictate which style of snow hole is more relevant. In Scandinavia and the Arctic regions, a ‘Kaloo’ or traditional Norwegian set up is the preferred choice. The idea is to dig a corridor straight into the snow pack and leave raised sleeping platforms either side. This has two distinct advantages: The first being that it keeps you closer to the top of the cave where the warm air from body and stove rises. The second is, as the cold air drops to the floor , it is allowed to escape through the doorway, which is in line with or often lower than the sleeping platforms - in effect acting as a cold sink. The roof has to be perfectly smooth and rounded to support the weight of the snow being exerted from above and the sides. In warmer climates, the Kaloo is prone to collapse.

Figure 2 The beginning of a Kaloo

In the British mountains, where the ambient temperature rarely drops below -10° and is more than often in the -1° to -7° range, it is more important to try and hold onto some of this cold air to stop the inner surface melting and dripping onto you. In this case a snow cave may be more appropriate. This can be dug quickly by two or more people, starting a planned distance apart, two doorways are dug in unison and joined once inside. The sleeping spaces are on the floor which encourages the retention of the cold air and expulsion of any warm air quickly.

Once the snow hole has been dug, the doors can be capped from the top downwards by cutting blocks from above the chosen site and sliding them into place.

Figure 3. The Kaloo - note the heat sink at foot level

Carbon Monoxide

Believe it or not more people succumb to Carbon Monoxide poisoning than by the collapse of their snow hole. Carbon Monoxide is produced from using a gas or petrol stove in an enclosed space and is formed when there is not enough Oxygen to produce Carbon Dioxide. Two essentials are needed to counter this. The first is a small hole punched through the roof with a ski or walking pole to allow the Carbon Monoxide to escape (CO is slightly lighter than air). The pole is left in place to clear any spindrift that may accumulate during the night. The second is a candle, (apart from the obvious extinguishment of the flame telling you that there’s not enough oxygen for the flame to burn) which should be slightly flickering to confirm there is a small amount of air circulation throughout the sleeping space.

Equipment

As we all know the mountainous regions of the world are amongst the harshest and unforgiving environments on the planet. The old adage of “there’s no such thing as bad weather, just bad equipment” holds true! Apart from having the usual ice-axe, crampons, water proofs, map, compass, weather reports and spare clothing, you should be equipped with an avalanche probe, snow shovel, bone saw, a good 4-season sleeping bag, a reliable stove and most important of all.... good quality training.

Neil Foote runs Backcountry Survival

Tags: snow, snowhole, winter

18 Comments

TinkyPete - 25-06-2012, 16:43
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Great article

Andy BB - 26-06-2012, 12:19
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A fascinating article - many thanks.

HOWEVER....i think this raises some very serious safety and preparation issues. I have to be careful here, as in the past I was censured for challenging the "sacred cow" of snow-holes as a survival aid (I was told - in pretty much these words "that what you call challenging sacred cows I call pi""ing on other peoples parades") So - to reiterate - this is a safety issue first and foremost, which I think ought to be discussed.

The article makes very clear that snow-holes are inherently dangerous - risks run from inadvertently initiating or being hit by an avalanche, simple collapse because of inadequate building, Carbon Monoxide poisoning through either having no vent, or having that vent freeze over/infill from drifting snow. Other risks include misjudging whats actually underneath the snow-hole you prepared, and excessive sweating during the building of it, with all the inherent risks thereof. The latter can be avoided by de-layering, but in the process you lose heat already trapped within the layers, and burn off substantial amounts of calories that may be difficult to replace if you're there for a while. And calories keep the body's furnace going, delaying the onset of hypothermia and death.

And the benefits? You're out of the wind - which is a big result, as wind-chill is a huge killer. And the temperature within the snow-hole can be raised to just below zero C. Any warmer and you have the added problems of the snow-hole melting, increasing the chances of collapse and adding wetness to an already hazardous situation.

THe article finishes by mentioning "must-have" equipment in these conditions - " you should be equipped with an avalanche probe, snow shovel, bone saw, a good 4-season sleeping bag, a reliable stove and most important of all.... good quality training". Anyone want to hazard a guess at the weight of all that? (Personally, if you intend to be sleeping in a snow-hole at temps around 0C, some sort of waterproof/breathable bivvy bag should be added, as wet sleeping bags tend to lose efficiency - down bags lose ALL efficiency!)

Is there any alternative? I believe so (although I must stress I have no link to, commission from, or actually own the product, or similar ones!).

And that is the Jerven bag. I referyou to their 2012 catalogue - http://www.jerven.com/main-catalogue-pdf and in particular page 64 and the SINTEF.. The originator explains it much better than I can, but in short, instead of digging a snow-hole/cave, you climb inside a Jerven bag. This not only gets you out of the wind, but the temperature will rise considerably above oC and stay there for days. (again see independent SINTEF tests). THere are various types of Jerven bag from unlined to heavy-lined, but even the most basic will keep you warmer4 than a snow-cave, and it weighs under a kg. Even the most thickly insulated only weighs 2kg. Chances are a "an avalanche probe, snow shovel, bone saw, a good 4-season sleeping bag," will weigh a lot more - even excluding the bivi bag!)

So - maybe the training companies need to reappraise their instructions? Maybe this is a sacred cow that needs to be challenged? Maybe the "essential equipment list" should include equipment that will do a better job of saving your life than the above-mentioned items? Maybe a mix of both? The Jerven bags (and their equivalents) are expensive, but then so is top-of-the-range climbing and sub-zero expedition gear. It is also - I would hazard - considerably lighter than the snow-hole alternatives. And bearing in mind the quote from the article above "and most important of all.... good quality training............."

Sacred cow? Heresy? Dunno - but it seems worthy of airing at least.....

Oh - one thing to add. I don't buy the excuse that I gather some trainers provide ie - don't know about it, haven't heard of it etc etc. These have been around for nearly two decades, and for people charging others for training in potentially life and death situations, they have a responsibility to keep abreast of developments, then make a rational judgement on their effectiveness or otherwise.

Wayland - 26-06-2012, 19:28
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Sensible enough advice Andy if you are carrying those tools just for the sake of snowholeing.

Having said that, I think that anyone travelling in those conditions should be carrying those tools anyway, in case of avalanche, so you would end up adding the weight of the Jervens bag (which might still not be a bad thing.) rather than replacing their weight.

ged - 26-06-2012, 20:05
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No mention of the gradient of the ground. Scary.

Andy BB - 26-06-2012, 20:06
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Originally Posted by Wayland

Sensible enough advice Andy if you are carrying those tools just for the sake of snowholeing.

Having said that, I think that anyone travelling in those conditions should be carrying those tools anyway, in case of avalanche, so you would end up adding the weight of the Jervens bag (which might still not be a bad thing.) rather than replacing their weight.

True enough. I suppose you could replace the sleeping bag with the insulated Jervens bag if weight was an issue...

southey - 26-06-2012, 23:05
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Hi andy, What's your experiance of the Jervans bag in cold too arctic conditions. What do you make of it?. I like the look of them.

Andy BB - 27-06-2012, 01:13
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Originally Posted by southey

Hi andy, What's your experiance of the Jervans bag in cold too arctic conditions. What do you make of it?. I like the look of them.

As I said above "(although I must stress I have no link to, commission from, or actually own the product, or similar ones!)" But, to be fair, there were times in the German mountains at -20C in the past that I wish I'd had one! My daughter's fiance is ex-Royal Marines, and told me that several of his opposite numbers on exercises in the Norwegian military had them and absolutely swore by them. Their brochure also has a number of testimonials from those on Arctic/Antarctic expeditions and Alaskan dog-Sled racing who were similarly impressed. I'm hoping to go out and play in the snow this winter (tickets and Gatwick parking already booked!) and hope to try a night out in one if I can raise the readies (and my wife doesn't have me sectioned for being so stupid before then "man of your age should know better etc etc" )

southey - 27-06-2012, 09:14
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Okay, I would just like to add this,

"from the Jervan website

Jerven currently produces six different Fjellduken models. The most basic product, Fjellduken Original, has no lining and weighs just 650 grams. The warmest Fjellduken, Fjellduken Extreme, is identical to the Hunter product, only with thicker lining. The most advanced product is Fjellduken Exclusive. It is a lined tarp without lining, but with zippers allowing you to connect PrimaLoft padding. This comes in 60gr and 170gr versions. All the thermoversions (With PrimaLoft) also work well as sleeping bag reinforcements. A number of Norwegian soldiers sleeping in -40 degrees Celsius weather have used Fjellduken products on the outside of their military sleeping bags.

Jerven also produces tents and hunting clothing in forest and mountain camouflage designs."

I have slept out in -40 a few times in snow graves, quinzee, tents, tree shelters, and very simple snow scrapes to just get out of the wind, all either on the central viddas of Norway or whist working around Banak air base in the north, using the British army Arctic sleeping bag, bivvie bag and clothing system, in relative comfort, I don't see why the jervan kit needs to be promoted above other good kit, maybe just as another option but not a be all,

I think the Article is quite poor, it gives limited info on the dangers and as said absolutely no mention of gradient, almost reads like an advert.

Andy BB - 27-06-2012, 11:02
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Originally Posted by southey

Okay, I would just like to add this,

"from the Jervan website

Jerven currently produces six different Fjellduken models. The most basic product, Fjellduken Original, has no lining and weighs just 650 grams. The warmest Fjellduken, Fjellduken Extreme, is identical to the Hunter product, only with thicker lining. The most advanced product is Fjellduken Exclusive. It is a lined tarp without lining, but with zippers allowing you to connect PrimaLoft padding. This comes in 60gr and 170gr versions. All the thermoversions (With PrimaLoft) also work well as sleeping bag reinforcements. A number of Norwegian soldiers sleeping in -40 degrees Celsius weather have used Fjellduken products on the outside of their military sleeping bags.

Jerven also produces tents and hunting clothing in forest and mountain camouflage designs."

I have slept out in -40 a few times in snow graves, quinzee, tents, tree shelters, and very simple snow scrapes to just get out of the wind, all either on the central viddas of Norway or whist working around Banak air base in the north, using the British army Arctic sleeping bag, bivvie bag and clothing system, in relative comfort, I don't see why the jervan kit needs to be promoted above other good kit, maybe just as another option but not a be all,

I think the Article is quite poor, it gives limited info on the dangers and as said absolutely no mention of gradient, almost reads like an advert.

Yes, I kinda gathered you were looking to make a point like that in your first reply - clearly an ex-forces man, looking to lure me into an ambush (possibly RM, as they spend so much time in Norway - or at least my putative son-in-law did?) Which is why I made clear in my first post I had no personal experience of them, and also pointed out in my first post - and the second one, for that matter "or similar systems". I believe that some units of the Israeli army, for example, make or use something similar.

You do of course make perfectly valid points based on personal experience, which is what I was looking for in the first place. As to the original article sounding almost like an advert, I'm presuming that it came from a guy who teaches cold-weather survival and such could be so construed - in the same way that the Jerven brochure highlights its own benefits. Which to me seem to include a significant weight saving (I also have an army arctic bag and bivi!), a major reduction in effort, calorie usage and sweat risk in building snow-holes/quinzees etc, and the significantly raised temperature compared to them (after all, a snow-hole - by definition - can't be warmer than 0C!). The SINTEF reports make interesting reading on that latter point. And - as you point out, snow-holes are fraught with dangers - a bit like scuba-diving in fact - you get it wrong, you die! (And yes - before you look to ambush me again, I am BSAC-qualified )

So - putting aside the internet chest-beating and point-scoring (I bow to your much greater experience in these conditions) and looking at it dispassionately, what's your view of the practical applications and usage of the Jerven bag or equivalent? If you had your time again would you see it as a positive benefit for your kit-list, or would you stick to the old tried-and-tested Army kit and methods? And if you were teaching cold-weather survival, would you at least reference it as an option to snow-holes etc?

southey - 27-06-2012, 11:06
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No, not looking to make a point, I hadnt looked at the site till after reading your post, but I do wonder at what product it was that they used around their bags,

ged - 27-06-2012, 11:07
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Originally Posted by southey

Okay, I would just like to add [...] I have slept out in -40 a few times in snow graves, quinzee, tents, tree shelters, and very simple snow scrapes to just get out of the wind, all either on the central viddas of Norway or whist working around Banak air base in the north, using the British army Arctic sleeping bag, bivvie bag and clothing system, in relative comfort, I don't see why the jervan kit needs to be promoted above other good kit, maybe just as another option but not a be all,

I think the Article is quite poor, it gives limited info on the dangers and as said absolutely no mention of gradient, almost reads like an advert.

All agreed. Having said that I have both the Jerven Thermo Extreme and the US army modular sleeping system (which I believe is supposed to be good for around -50 with the right clothing) and I do tend to prefer the Jerven. That's mostly because it's both more flexible and a lot roomier -- which is part of the reason for its flexibility.

The Jerven bag and a four-season sleeping bag is my favourite setup for cold weather, nice and simple, flexible, and toasty warm well below -20. I've been out meteor-spotting with the wife in the Peak District at -15 in a near gale, and with just the two of us, dressed normally in Jerven bag flopped down on the snow we had quite a cosy night even with our heads sticking out of the bag looking for flying rocks. She wouldn't have stayed out in those conditions in anything else I could offer. I really like that you can sit up in the Jerven bag, unzip a couple of little holes for your arms, and get a brew on without even getting out of the bag. On the other hand if the weather is wet I prefer the bivvy, the zips and fixing points on the Jerven bag are IMO weak points for water ingress. Much above zero and I get too hot in the Jerven bag anyway, and mine doesn't have a detachable lining like some of the newer ones do. Horses for courses.

southey - 27-06-2012, 11:14
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Sorry Andy just re read the last bit of your post, I honestly wouldn't see it as a benefit,UNLESS i had the heavier bag and was sat on stag(wont happen at those temps) the quick nature of its shelter is a benefit, but then a well known tent can be erected in very short order and a stove lit inside for warmth and food, don't know if you can cook under a jervan, you can also cook inside a quinzee, snow hole, snow grave whilst inside your sleeping bag(with the stove outside of course) I can honestly say I could only see this product as another form of shelter, and as for time over again, im still in my time And certainly not a Booty!

southey - 27-06-2012, 11:21
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As for recommending it, I cant, I haven't ever used one , Would like to have a play though, maybe a new thing to save for!!

BackcountrySurvival - 27-06-2012, 17:56
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Thanks for the comments guys all valid points. The article is written as there isn't a lot of information on Mountain Survival on BCUK. All our instructors are members of MLTB and are trained and qualified Winter mountain leaders or hold Mountain instructor certificates and have been involved in expeditions to Siberia, the Himalayas, Norway......There's no substitute for experience.

johnboy - 04-07-2012, 18:11
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Interesting article....

gadgetdragon - 10-07-2012, 03:23
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As a scotish winter climber and alpinist I have had experienced on a number of occasions sleeping in a snow cave, a very wet and damp experience in the warmer scotish mountains. Much dryer/colder in european regions. You have so much gear to carry on a climbing trip there is only room for essential gear and as with bush crafting you have to rely on what you have. The backing out of your rucksac makes a perfectly good snow shovel. A saw is useless in scotish snow. A good sleeping bag and bivi bag is what any sensible mountaineer would carry as standard. You don't go looking to go snow caving it what you do in an emergency to keep you alive, so out with the health and safety issue. Just learn how to do it and make it part of your skill set should the need arise.

gadgetdragon - 10-07-2012, 03:25
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By the way nice concise article :-)

Noddy - 10-09-2012, 16:05
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It's true that you do have to remember to be a bit anal about not touching the walls, even if it is nippy outside

Also I have never got less than very wet making one Snow down the neck, soaked gloves, all that ... have to learn to be anal about that too, I guess

Thanks for the article, Tony