by Andy Selters
With time most slopes either strengthen or avalanche, although instability can persist for weeks in cold regions. Avalanche prediction blends refined science with experienced guesswork, and all alpine travelers should get training in it.
David Wilson exiting the Yerupajá Glacier, Cordillera Huayhaush, Peru
SERAC FALL
Wherever a glacier pours over a steep area the ice breaks into walls and seracs that periodically tumble. These ice avalanches are mountaineering's most awesome hazard. Expeditions spend considerable time assessing the relative danger of different areas of serac fall, then taking careful steps to minimize exposure time in the danger zones.
If avalanche study mixes some guesswork with refined science, then predicting serac fall mixes precious little science with a world of guesswork. In this game there is only one certainty: walls that have released blocks in the past will do so again. The pertinent questions are, how often does a given wall release, and what area will be hit?
When assessing the hazard to a certain area, know that if seracs look unstable and tottering, they are. Ice walls that have scalloped, fresh facets have unleashed a cataclysm recently, and you can probably see the crumbled fragments on the ground below. Look carefully (from a distance!) at the amount, scale, scope, and freshness of this debris. Sometimes these fragments are lightly buried under new snowfall, and show as “tombstone” lumps on a debris cone. On an expedition, try to watch the area for many days while you get used to the altitude and plan your trip. In any case, make a guess as to whether the walls in question calve daily, weekly, monthly, annually, or hourly. Then compare your estimation of calving frequency with the time you expect to spend on a possible route in the danger zone. Usually, each serac area has active spots that release repeatedly for awhile. Places that are obviously suicidal as well as places with minimal serac hazards are easy to figure. It's the seracs that only go occasionally that make for tough decisions.
Climbers have spent countless hours pondering how much melting daytime temperatures help trigger serac fall. It certainly seems as if serac fall activity goes up during the day, but every mountaineer has heard the sound of icefall from a sleeping bag. Teams that must weave through serious icefalls, such as south-side routes to Mount Everest, often set a noon deadline to be out of the danger zone. Some experienced climbers say that serac fall increases at the warmest part of the day, and also at the coldest wee hours. This may be because very cold ice is more brittle and therefore weak. Heavy snowfall puts added weight on seracs, which also increases their likelihood of calving. Finally, anecdotal evidence suggests that seasons following especially heavy winters may have a higher rate of serac fall.
Although we ponder much to distinguish relative safety from relative hazard, smart decisions are based on the knowledge that the constant of gravity is the primary force behind serac falls, and so the only sure way to reduce the chance of getting hit is to spend less time under serac walls. Certainly climbers should avoid placing camps or taking rest stops in hazardous areas. Even under relatively safe seracs, if there is a safer spot nearby, stack the odds in your favor and keep going to the safest spot around before stopping.
GATHERING TOGETHER
Most rest stops can be taken with the members still stretched apart along their rope, but when a team does gather together to rest or camp, the lead member and the party as a whole must choose the spot carefully. Compression zones with little chance of hidden crevasses and no hazards from above make the best spots. But even there, if there is any chance that the area might hide crevasses, the leader should probe it with the rope still stretched out. Then the last member into the site should be brought in with a belay from the adjacent member For campsites, the established “safe zone” should be designated with marks or wands. When leaving the zone the process is reversed—;the leader gets a belay as he stretches out the rope.
TRAVEL ON A “DRY” ABLATION ZONE
Where no snow covers a glacier's ice skeleton, travel precautions are much different. There are no snowbridges to break through and all the crevasses are apparent. But to simply travel roped up as on a snowy surface is to court disaster; members cannot hold falls on the ice, and a rope merely assures that one person's fall will include the rest. Hence, members travel unroped as they would on rock or general alpine terrain, unless the climbing is steep and/or exposed enough to require an anchored belay.
CAMPING CONSIDERATIONS
Disposal of human waste is a serious concern on a glacier, and there is no ideal answer The first choice is to defecate off the glacier in soil or moraine where water contamination is minimized. If you must go on the glacier get the waste into a deep crevasse. Usually in camp this means you dig a potty and line it with a bag stretched out between wands for later transport to a crevasse. Bags should be either biodegradable plastic or (in fair weather) paper grocery sacks, doubled in either case.
Another possibility on a temperate glacier in the summer is to camp near a crevasse with a solid edge, making this a direct latrine. Set an anchor and fix a rope to the edge, making sure that there's no overhanging lip (or else clearing a small lip away), and with a swami tie-in and prusik self-belay members can lean back and, well, unload. Direct crevasse latrines are certainly preferred while on the go, and for this reason it's better to have a harness with leg loops that drop away, or else you'll have to rig a separate waist belt.
Camping near a solid crevasse also allows sound disposal of urine and food waste. If a solid-edged crevasse is unavailable, a urination site should be designated so the waste will be concentrated. Remember that on a glacier the water source is the snow.
We can only speculate if crevasse-buried waste does or does not contaminate glacial melt-water; certainly much depends on the type of glacier and the distance from the terminus. But crevasse burial is certainly better than surface burial, which melts out.
Some land managers now require that all fecal waste be carried out. Kayakers' dry-bag technology can help make this a simple, hygienic operation. All litter should be carried out, just as in any backcountry area.
A couple of final aesthetic courtesies: camp at least a short distance off a well-traveled trail so other climbers don't have to walk through your campsite; and retrieve and pack out any wands you've placed.
Greg Collum working through a moat/crevasse complex on the Tiedemann Glacier, British Columbia Coast Mountains
CHAPTER 3
RESCUE TECHNIQUES FOR
THE GLACIER TRAVELER
The previous chapter discussed the precautions that glacier travelers can take to guard against crevasse falls. But being prepared and careful doesn't change the fact that an occasional fall into a crevasse is a part of traveling on glaciers. Therefore, knowing how to ascend out of a crevasse and how to haul a partner out of one have long been acknowledged as essential skills for the glacier traveler This chapter outlines the fundamentals of these skills, and the following chapter adds more advanced techniques to make crevasse rescue reliable in more situations.
ASCENDING SYSTEMS
Most crevasses trap victims between unclimbable walls of soft snow overhung by looser snow. So to get out of a typical crevasse a person needs to have a system for ascending the rope. Big-wall climbers, spelunkers, and glacier travelers all have developed various systems for ascending a rope. Each system uses a set of two or more rope-gripping devices, either mechanical ascenders or prusik (or similar) knots. With all your weight on one ascender or knot, the other, unweighted one can be moved up the rope; then you shift all your weight to the “new” one and raise the other repeating the process up the rope. As well as using various knots or camming devices, systems differ in how they connect body parts to the knots or ascenders.
The prusik knot has served as a tried-and-true rope-gripping device for decades now, and all glacier travelers should be practiced with it. The Bachman variation (see Appendix 2) is favored by many for ease of movement. Tiny mechanical devices offer even greater convenience and easier
operation than knots. Full-size, “big-wall” ascenders are also faster and easier to use than knots, but few glacier travelers justify their weight and expense unless they need them anyway for their climbing objective. Some do not grip well on icy ropes. With any mechanical ascending device, one must be careful to not install it where it might receive a shock load, as this can damage the rope. It's also best to avoid putting shock loads on prusiks or similar knots, for unless they are already set tight they can slip and be burned by the sliding rope.
A prusik knot is made from a loop of supple rope, usually 6-millimeter perlon. The best knot to tie the loop is a grapevine or “double fisherman's” knot. To make a prusik knot from the loop you simply wrap it through itself two or three times around a rope of larger diameter (see fig. 3.1). Essentially, then, the prusik knot is a double or triple girth hitch. Straighten the wraps so that they coil cleanly and snugly around the main rope. The wraps grab when you pull on the open loop, and, up to a fairly substantial force, the more you pull the more tightly they grab, because the wraps are snugging onto themselves. But when you loosen the wraps and hold them directly, they slide freely along the main rope. After a person's body weight has wrenched the wraps tightly, an easy way to loosen them is to press against the single “opposing” wrap designated in the drawing.
A prusik's friction relies on the suppleness and smaller diameter of the prusik cord. With climbing ropes of either 9 or 11 millimeters in diameter, the best compromise between strength and bite is a 6-millimeter prusik. However, a somewhat stiff 6-millimeter prusik on a somewhat stiff 9-millimeter rope will definitely need that third wrap to keep it from slipping. When new, a single strand of 6-millimeter perlon rope will hold up to 1,700 pounds, but it should nevertheless be replaced frequently. Some climbers favor marine-braid Dacron cord for their prusiks because its very supple sheath grabs extremely well. However, be aware that this softer sheath wears faster than the stiffer but tougher perlon. The new nylon-sheathed, 5.5mm Spectra cord is a suitable, prusik material that's essentially as strong as a climbing rope, although even the softer weaves are a bit stiffer than perlon. Kevlar cord should never be used for a prusik because it's quite stiff and its fibers readily break down with repeated flexing.
Figure 3.1 Tying on prusik knot
Of all the connecting systems, the Texas system has drawn the most favor among glacier travelers for its simplicity, lightness, comfort, and ease of use. It consists of a simple prusik loop (made from 40 to 45 inches of cord) clipped to a locking or doubled carabiner on the seat harness, plus a second prusik knot with a pair of extensions and small loops for the feet (see fig. 3.2).
The foot loops, or “stirrups,” are best constructed from a single strand 10 to 12 feet long, as follows:
In the middle of this strand tie a figure eight with a bight at least 6 inches long.
Stand and hold this bight at your diaphragm with the two strands draped down to the ground.
At the point where each strand reaches the ground, tie an overhand knot that leaves a bight of about 3 inches. Test your system, and trim off any extra cord.
Figure 3.2 Texas prusik system
To make these overhand knots into a cinching loop for a boot of any size, with or without crampons, you simply feed the main cord through the loop as a girth hitch–feed your boot through, and cinch the hitch tight.
Another option for making the foot loops is to tie sliding hitches with stopper knots. Tie an overhand “stopper” in the foot strand, and then with the end tie an overhand around the strand, so that will slide up and down. Adjust the position of the stopper knot to a position that holds a loop that fits your boot size. This setup has the advantage of not constricting your foot, but it is less adjustable for use with and without crampons.
For climbs with more technical climbing and less glacier and crevasse hazard, it's reasonable to save on gear by counting on being able to improvise a foot prusik from your cordelette should you fall in a crevasse. If you do end up hanging in a crevasse, wrap the cordelette around the rope as a prusik knot, and then tie figure-eight bight loops for one or both feet.
When roping up for glacier travel, you'll need to decide whether to travel with prusiks already in place on the rope. In general, if the crevasses are numerous and the surface conditions uncertain, the minutes it takes for each member to wrap her prusiks on the rope can be time well spent in the case of a crevasse fall. If the crevasse hazard is light and the day likely to require more technical climbing than glacier touring, it will be more efficient and safe enough to travel with prusik cords simply knotted and kept handy on the harness gear loops.
For traveling with prusiks in place, wrap both the waist and stirrup prusiks on the rope between you and a partner the stirrup-cord adjacent to your harness, the waist loop next to them. Clip the waist prusik to a locking carabiner on the harness, and either tuck the stirrups away in a pocket, or knot and clip them off on the harness. Make sure that the waist prusik connection to your harness has slack, or else it will take the force of a fall.
If you're using mechanical ascenders, keep them handy on the harness, not on the rope, because in a crevasse fall the metal objects spring up at about face level. Also, some can damage or even cut the rope if they take the force of a serious fall. Most models can readily be put on the rope when needed. Among the mini-ascenders tested for this book, the “Ropeman” gets praise for a secure camming grip on the rope. The “Tibloc” is wonderfully light and simple, but the user must be careful to make sure it grips before weighting it, because if it slips its sharp teeth can damage the rope. In any case, use ascenders like prusik knots, and travel with cord to attach them to your harness and feet.
Here's a summary of how to ascend with the Texas system (see fig. 3.3a to c):
Hitch your feet into the stirrups, then stand tall in them.To keep strain off your arms while standing up, bring your feet under your buttocks and press up using your thighs (see fig. 3.3a).
As you rise, loosen the waist prusik and slide it up the rope with you (see fig. 3.3b).
Sit back on the waist prusik and lift your feet as high as possible (see fig. 3.3c).
With the weight now off the stirrups, slide them up as high as possible, even to where they meet the waist prusik.
Kick your feet under your buttocks to stand tall and repeat the process.
The Texas system keeps your weight balanced by having you straddle the rope, and you spend over half your ascent time hanging relatively comfortably in your seat harness. Chest harnesses interfere with raising the waist prusik in this system, so they should be unclipped while ascending.
In any ascending system the only safety is the prusik or ascender that connects to your waist harness. As reliable as most systems are, if you're ascending more than just 15 or 20 feet it's wise to back it up by clipping a bighted figure eight from the main rope right below the lower prusik or ascender into another locking carabiner on your harness.
Whatever ascending system you use, however it's important to practice using it before it's needed; throwing a rope over a tree limb can make for at least a rudimentary practice session.This is also the best opportunity to adjust your stirrups and waist loop to the optimal lengths.
PRUSIK OR ASCENDER AS SELF-BELAY
A prusik or ascender can also be used to belay oneself along a rope on a glacier's surface. The prusik or ascender connects from a taut, anchored rope to your seat harness. With full-size ascenders you should clip a carabiner from the bottom of the ascender across the rope; this keeps the ascender in line with the rope. This is advised because when you fall at 90 degrees to the anchor's axis such ascenders tend to lever off the rope. With the prusik or ascender set up, you're free to move along the rope in either direction, sliding the prusik or ascender as you go. Should a snowbridge fail, you must let go of the prusik or ascender and let it hold your fall. Just as for ascending, it doesn't hurt to back this up with a figure-eight knot clipped into your harness as well. Self-belays come in handy during
crevasse rescues; the situations when you're likely to need one are described later.
Figure 3.3a Ascending with the Texas prusik system, using leg muscles to bring the feet under the buttocks, then stand tall
Figure 3.3b Stand tall, bringing waist prusik up as you rise
Figure 3.3c Resting from the waist prusik, slide the foot prusik as high as possible
VICTIM PROCEDURES
One moment you're walking on top of the glacier, the next you're falling, plunging through a chaos of snow and darkness, seemingly into the bowels of the earth. Then, boing! You're jerked to a swinging, sputtering halt, and you look down between cold blue walls into an apparently infinite, dripping blackness.
Your heart races and you strain against a weight still pulling you toward the depths. Oh yes, you recall, the first thing to do after falling in a crevasse is to get your pack off your back, and clip it onto the rope. If you were traveling with the pack already clipped to the rope, you can just heave it off. Eventually you'll want to have it clipped to the rope below your prusiks or ascenders, but for now just get it onto the rope. You can also clip off your ice ax. You may be warm with adrenaline now, but the wet darkness of a crevasse will soon chill you, so next put on some more clothes, especially to keep your hands warm.
Now look around. Is it at all reasonable to walk, climb, or chimney out of the crevasse? Soon one of your buddies will be peering down at you, and a belay or lowering can be arranged. If, however you can't climb out, and if you actually are dangling in space with your full weight on the rope, there's no reason not to simply start ascending it. True, you don't know what kind of anchor your partners may be rushing to set up, but with your weight already fully on the rope, unless your ascending system fails there's nothing that ascending can do that they'll even notice. However, if even part of your weight is not on the rope−for example, if you're on a ledge or pressing between crevasse walls—don't surprise your partners with any additional load. In this case, wait for someone to peer over and assure you that the rope is well anchored.
