Snow and Ice 2017-04-08T21:33:29+00:00
Snow and Ice

Enjoying the White Stuff

Snow Travel

An ice-axe and knowing how to use it is essential on all but the easiest soft snow slopes with good run-outs. If you only have a walking pole, ensure that you know how to self-arrest with it, though even with an ice-axe, self-arresting is not guaranteed to stop you. When holding an ice-axe by the shaft on flat ground, it is good manners to keep the shaft pointing forward. When using it, keep your ice-axe in your uphill hand, with the pick pointing backwards unless you are front-pointing.

In general, keep your feet as flat on the snow as you can, though if you are not wearing crampons, on firmer snow you will need to ‘edge’ your boots by scuffing the uphill edges of your boot soles into the snow.

If wearing crampons, walk like a horse-sore cowboy to ensure that your front-points don’t catch on the back of your gaiters, which could easily lead to a fatal trip; all ten points should grip the snow.

Subsequent party members should always place their left feet in steps made by the leader’s left foot and vice versa to avoid off-balancing those following.

Keep your feet dry when travelling in powder snow; a plastic bag inside wet boots will keep your feet dry for a good part of the day. Keeping the bag intact as you put your boots on takes patience and practice.

Sunglasses are essential, even on overcast days, to prevent snow blindness. Ordinary glasses are quite good at protecting the eyes from ultra-violet rays and can be substituted, but they won’t stop the glare, which may give you a headache.

Step chopping

To cross short sections of hard snow on moderate slopes without crampons, you will need to chop steps. Attach the ice-axe to your uphill wrist with the leash to help support your hand and to prevent losing the ice-axe should you drop it. Stand in a position of balance, hold the ice-axe with both hands and aggressively swing the adze in front of and a little above your uphill foot to scoop out a new step for your downhill foot. Start at the heel end of the new step and work towards the toe, aiming for three chops for each step. Next, chop a step for your uphill boot, directly above the downhill step. Advance to these steps and start again.

Swing the ice-axe from your shoulder, cutting with the adze and letting the weight of the ice-axe do most of the work. The ice-axe should follow an arc, assisted by lifting your uphill elbow during the final phase of the chop, rather than hacking directly into the ice. Get into a rhythm: chop-chop the first step, pause, chop-chop the next step, pause, advance feet… Don’t chop the steps too far apart if you are likely to descend by the same route.

Ascending and descending slopes

Zig-zagging is the easiest way to make height on moderate slopes. In steeper, soft snow pigeon-holing is best, but remember to stand upright as the slope eases. When descending, try to face outwards rather than into the slope, maintaining your weight directly over your heels.

A danger later in the day is finding, either going up, or down, that hitherto soft snow now has a hard layer of snow, or ice coming to the surface. This can be lethal without crampons. If you are wearing crampons, they may ball up under such conditions and so also pose danger – tap their sides with your ice-axe, at each step if necessary, to dislodge balled up snow.

Bum-sliding and glissading are fast ways to descend, but never, ever do this on hard snow, where there is a poor run-out, or while wearing crampons. Be aware that by far the most alpine accidents occur on the descent.

Belays

For tramping, a waist belay will likely suffice. Ice-axe belays are no longer recommended except to protect a second person through a short section, where a lead fall is impossible. 

Snow anchors

Snow stakes are the preferred snow anchor, but they need very careful placement to protect lead falls on steep terrain. If in doubt, use the snow stake as a deadman, or use an ice-axe as a deadman back up.

Avalanches

Predicting avalanches

Accurately predicting avalanches is impossible, but experience and understanding goes a long way. You can improve your odds by observing similar nearby slopes (gradient and aspect) and knowing the recent snow-fall history. Be aware of the slopes above you.

  • 90% of all avalanches occur during a storm, or the following day,
  • Slopes steeper than about 50° to 60° tend to slough snow constantly when it is snowing, while it is rare for slopes less than 25° to avalanche,
  • 25cm of new snow, or more than 2cm/hr snowfall means slopes over 30° are prone to avalanche,
  • Squeaky snow underfoot indicates wind pack and the possibility of slab avalanches, especially if the slope is between 30° and 45°, or so. Lee slopes, often indicated by cornices, collect more snow than windward slopes due to drifting and are thus more susceptible,
  • Slab avalanches are most easily triggered at, or just below a convex part of the slope,
  • Basins and gullies have many different aspects and so are also dangerous,
  • Wet snow avalanches tend to occur in the afternoon on sunny slopes as the snow thaws. They can occur on slopes less than 30°,
  • Moderate, or heavy rain, and recent heavy snowfall are often indicators of high avalanche risk.

To estimate the angle of a slope, note that a fist at arm’s length spans 10° between the outside of the knuckles: start with the top of one fist level with your eye and place fist after fist on top of each other to meet the slope. One knuckle width is 2 ½°.

If caught in an avalanche

You have a very small likelihood of surviving a decent sized avalanche: if the fall from being swept over a bluff doesn’t kill you outright, expect to suffocate, immobilised in the snow. When the avalanche stops, it quickly sets concrete-like. You can increase your chances of survival by keeping your mouth closed and when you stop, try to make an air space in front of your face. Your only real hope is that you stop near the surface and someone can get to you in a few minutes. More people die in small, local avalanches than in larger ones. If travelling in country where avalanches are a possibility, strongly consider taking snow shovels and avalanche transceivers.

Glacier travel

Think of a glacier as a slow moving river: crevasses are often found where a rapid would form in a river and icefalls where you would expect a waterfall. Unless the glacier is “showing its bones”, or it is clear that there are no crevasses, rope up. Avoid travelling parallel to the line of crevasses.

The “Kiwi Coil” is now standard technique for roping up. The tension on the rope is equally spread between the shoulder coils and your harness. Two person parties should tie loops with figure of eight knots at 1 ½ metre intervals in the rope to increase friction should someone fall into a crevasse.

If the likelihood of encountering hidden crevasses is high (e.g. after snowfall, or late afternoon in summer), the leader should probe continuously while the second belays. Snow bridges tend to become soft in the afternoon; at any rate, it is prudent to belay across them.

Crevasse extraction

Once someone falls into a crevasse deeper than their shoulders, the problem of getting them out is no longer trivial. A person dangling on a waist belt will become unconscious within ten minutes or so, as the blood supply is cut off. A climbing harness will give you up to half an hour, or so if you are imobile. It is important for the victim to get his, or her feet into a prusik loop to transfer weight off their waist as soon as possible and also to provide leg resistance to allow ‘pumping’ the leg muscles to improve blood circulation.

 

Scrapbook

The well-dressed tramper above the snowline wears shorts and long-johns, a fashion combination since the early 1970s. And, of course, an ice-axe is an essential accessory. Dark glasses prevent snowblindess- a possibility even on overcast days.

 

Jumping small crevasses or “slots” in a glacier “showing its bones” in summer is usually straightforward.

 

Putting on crampons is easiest when you can stick them into the snow. Remember that any buckles always go on the outside of the foot (there is a left and a right crampon!).

Wilderlife