Monday, April 5, 2010

4-3-10 Revisiting the avalanche track in Ammonoosuc Ravine

I arrived at the base station of the Cog Railway a few minutes before 9 am on Saturday (4-3-10) to find the parking lot full and literally hundreds of skiers making ready to hike and/or "skin" up the west side of Mt. Washington. It was astonishing just to see the sheer numbers of people spilling up the mountain. In part it was due to the weather which had been forecast to be perfect with clear skies, lots of sun, and near-record breaking for warmth. The other parts, though, are the growing interest in Alpine Touring/"backcountry-telemark" skiing as in getting away from crowds, expensive ski lifts, etc, and the accessibility of the west side of Mt. Washington in the winter and spring now that the Base Station Road is plowed and open all year.

Seeing the crowd on Saturday was reminiscent of past decades at Pinkham Notch (this photo was taken in the 1930s by my dad) when, on weekend afternoons from early March to late May (or sometimes 'til early June), the front yard of the Trading Post would be crowded with sunburned skiers just down from Tuckerman's Ravine, the Upper Snowfields, or the Gulf of Slides. The number of automobiles in the parking lot added to those parked up and down both sides of Rt. 16 for miles was and still is astronomical every weekend of the spring skiing season without fail. I made my debut in this ritual in 1950 and still have intense nostalgia (that probably borders on psychosis!) and a strong sense of camaraderie with all those seasoned generations of skiers who for decades rarely missed a spring weekend in "Tucks" and think of the "Ravine" as a truly magical, majestic place. Each generation that comes along seems to discover it anew and adds its own character to that long tradition. I think my earliest memories of hiking into the ravine with my friends, accompanied by assorted fathers, was the blue sky against the rocks and snow, how the sun reflected so brightly from that world of snow and could turn you to toast in an instant, all the other characters hiking up with their skis over their shoulders, the camaraderie, and. best of all, the wonderful smell of the balsam firs along the trail.

Seeing so many skiers on the west side of the mountain attests to a new generation looking for it's own niche, but it really underlines the intense over-crowding on the east side of the mountain. The west side seems to attract skiers who use Alpine Touring (AT) ski equipment that's designed for back country skiing in steep mountain terrain. A lot of skiers on Saturday were walking up in their boots right on the cog tracks or "skinning" up on their AT skis using the right-of-way next to the tracks. Others, like this couple, were packing their skis as they headed up the Jewel Trail, the most direct root to the Great Gulf where they were planning to ski for the day. The Great Gulf has become a popular destination for extreme skiers during the past 20 years.

This knot of skiers was just a small sample of the vast number that paraded up the mountain as I got my own equipment ready.

Anyway, it felt good to get back on the Ammy and head uphill and fight gravity. It was relatively hot and at 9:10 am was already 50 degrees (F) at the base station and promising to be that hot up on the ridge. The snow in the woods, with the deep wells around the base of the trees, attests to warm temperatures over the past few days.

The river was still deeply covered by snow pack, for the most part, and made hiking a little easier. This is looking straight into Ammonoosuc Ravine and up at the summit of Mt. Washington.

This is looking into Ammonoosuc Ravine from the large opening created by the recent avalanche. Enough snow has melted over the past month to uncover some of what must be a massive amount of debris that came down the mountain with the avalanche.

This is what the same view looked like on 3-4-10, exactly a month ago.

If you look carefully you can make out skiers, tiny dots, on the upper areas above these gullies. For clarity I'm going to name the gullies "Central", the one straight ahead, and "Right" for the partially hidden gully one the right. I climbed 2/3 of the way up central gully to try and get an idea where the avalanche started and whether it replicated the route taken by a large avalanche that occurred here in the winter of 1969-1970. I hiked up and over the ridge via the right gully thinking of going to the summit. It was in the mid-50 degree range on the ridge and the sun was scorching. Someone I passed commented that they thought it was about 70 degrees over by Lakes of the Clouds which would easily have been a record. Later I read that the Observatory's high for the day was 50 degrees (F).

Skiers and snow boarders were everywhere starting early in the morning. They were streaming down all the gullies and, for that matter, the areas between the gullies. Everyone was excited by the quantity and the quality of the snow at least in the first half of the day. By noon the texture had gone from "corn" to something resembling mashed potatoes.

A group from Canada skiing and snow boarding on Mt. Washington for the first time. For Canadians coming south through Vermont the west side of the range is an hour closer (less driving) then the east side. For as long as I can remember Canadians have been some of the most dedicated denizens of Tuckerman's Ravine each spring. They've been at the forefront, as well, of opening up new areas and skiing the more extreme "lines" all over the mountain.

The January 2010 avalanche probably started a little ways above this bowl, probably just above the crevasse that's opened up and just below the chute where the gully is at least a 50 degree incline and where there was a high downward pressure from gravity, less friction and lowered cohesion at the lowest layers of snow. This bowl is about 2/3 of the way up the central gully. The vegetation in the center of the photo is undamaged while the alpine birch in the vicinity of where the photo was taken is scarred from the movement of the snow.

In the right-hand gully the avalanche began below these birch trees near the top of the gully

and probably close to this spot located about 2/3 of the way up the gully.

Looking down from where the above photo was taken the slide track is clearly laid out along with the extent of damage it did as it hooked right and then left down the valley, sweeping high up on the lower, opposite ridge. The massive volume of snow and it's speed is indicated by the large swath . It's likely that the avalanche was comprised of dense, wet snow with the consistency of a slurry due to excessive rain that fell during the 2-day period just prior to the slide.

Two skiers on the slide track at the confluence of the right and central gullies. Two separate avalanches, one from each of the two gullies, must have joined here. The avalanche was a form of "mass wasting" in that many tons of material were moved away from the side of the mountain and carried downstream where it was dumped in the main channel of the Ammonoosuc River. By volume most of the material was snow and ice. It won't be possible to assess how much rock and gravel was moved until after the snow has melted, but it is obvious that thousands of trees, mostly birch and balsam fir, were destroyed and a large open area created in place of the forest.

A better look at the avalanche track just below the confluence of the central and right gullies. This form of mass wasting, like landslides, is dramatic evidence that, although we think of the White Mountains as hundreds of millions of years old, they are still young in some ways, still moving and still feeling gravity pulling them down to be, at some point, a level plain. The avalanche, to the mountain, is like the beat of a pulse; a sign of life . The devastation, too, is just a blink of an eye, an "aufblick", in the long, long life of these rocks and forests.

This is the corner, seen for above, where the avalanche turned sharply to head down the valley. Like a bobsled in a chute the avalanche, with all of its weight and momentum, slid up on the ridge in the background mowing everything down in its path. It must have made a lot of noise although the snow may have muffled a lot of the sound.

I heard from skiers back at the parking lot in the afternoon that they had seen similar avalanche tracks in Burts Ravine, located just north of Ammonoosuc Ravine, and in old avalanche track that descends from the col between Mt. Monroe and Mt. Franklin just to the south of Lakes of the Clouds. It seems probable, then, that Ravine of the Castles and Kings Ravine also had big avalanches as they also face northwest and the storm that dumped all snow came in from the southeast.

Once the snow has melted we'll be able to assess the full amount of damage done and the extent of the debris that's still under the snow. In another month or two, with most of the snow melted, it will probably look even more impressive.