Friday, April 3, 2009

Alpine Snow and Ice—Working with a Mercurial Medium

Alpine climbing owes much of its complexity to the changeable nature of snow and ice. Experience, prior research, and good technique can help you adapt to the conditions you encounter on the mountain. The first step is appreciating just how much difference conditions can make. An illustrative example can be found in the North Face of Mt. Shuksan.

Shuksan's North Face. Forest McBrian

A Cascades classic, the North Face is long and moderate: 2,500’ of 35 to 45 degree snow, with a few sections at 50 degrees. The lower part of the face is formed by a small hanging glacier with several significant crevasses. Passing briefly beneath a hanging icefield and up a narrow gully, the route gains the long, steep snow slopes of the upper North Face and follows them to the mountain’s high plateau at 8,000’.

The first time I climbed it, the North Face glowered from the shade. It was mid-October, and the long hot summer, followed by the autumn freeze, had hardened the snow into ice. Selected Climbs in the Cascades had warned us, “Sharp tools and crampons will take care of the hard ice encountered this time of year.” Indeed, even the short sections of easy rock scrambling were streaked with verglas (a thin veneer of refrozen meltwater), making sharp points vital. Even well equipped, it was a long, strenuous climb, with lots of front pointing. We climbed with running belays, clipping the rope between us into ice screws and moving together. Eight hours on the face turned our triceps and calf muscles to jelly.

Five years later, I had the opportunity to guide an AAI climber up the North Face. It was early September, and the forecast was excellent, if a little warm. Temperature is not the only factor, however. A clear night allows for long-wave radiative cooling, which can have an almost magical firming effect on the surface snow. As we set foot on the face it was no colder than 40 degrees fahrenheit, and yet the snow remained a perfect styrofoam consistency for the duration of the climb. The face yielded to relaxed French technique, with judicious use of troisieme and just a little front pointing. We pitched out the upper, steeper face in order to provide more security to my partner (Remarkably, it was only his fourth day of ice climbing ever!). The belays went in quickly—perfect vertical pickets—and we made great time. Even pitching it out, we spent only six hours on the face.

This past year I went back, again with a former climbing partner from AAI. Mike and I had summitted Denali together, and I was pleased to be climbing with him in my home range. It was July, and a heat wave had me a little concerned. I knew that we might have to turn around if the snow proved too soft; the foundation of our security in the mountains is always balanced, secure movement, and slushy, unpredictable step-kicking can quickly turn precarious. But a clear, starry night at the bivouac reassured me a little. We set out in the morning, and the lower face proved discouraging. A thin crust had formed, and it was difficult to establish a rhythm; the snow supported one step, but not the next. Things slowly improved, however, and by the time we exited the gully, we had begun a perfect staircase up the face. Although kicking the steps was strenuous, the result was extremely secure footing. Belay anchors, had we chosen to use them, would have required t-slotting pickets in the soft snow. Confident in Mike’s footwork, I chose to move together on a shortened rope for almost the entire route, topping out on the shoulder after only four hours.

Snow and ice routes change dramatically through the season. The security of movement changes accordingly—the bucket steps of July become the bullet-hard front pointing of October. According to our comfort with a given technique, we adjust our roped travel scheme, from moving together on a short rope, to running belays, to full-blown pitches. It is interesting to note that conditions influence speed not only by influencing rope technique; my first climb was slower than my second, even though in theory running belays should be faster. The climbing itself was simply slower and more strenuous the first time around. Notice, too, that the same terrain alternately required t-slots, vertical pickets, and ice screws, according to the snow conditions.

Knowing the conditions before you go is ideal, but not always possible. Being prepared with the right repertoire of techniques, ample fitness, and appropriate gear will help you be ready for the unexpected. Most of all, mileage on snow and ice all through the seasons will help develop the intimacy with the medium that is key to more advanced climbs. Climbing the same route multiple times under varied conditions is a great exercise, and the sign of a dedicated student of the mountains.

-- Forest McBrian, AAI Guide

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