Wednesday, May 19, 2010

5-14-10 Avalanche Track in Ammonoosuc Ravine

This was the first sign of debris from the truly massive avalanche that descended Ammonoosuc Ravine in January and carried thousands of shattered trees far down the mountain. My daughter, Liz, and I hiked up the avalance track in a mist of rain on Friday (5-14) to assess the damage to the forest on both sides of the Ammonoosuc River. The damage is mind boggling and suggests something more on the magnitude of an atomic bomb blast than a mere snow avalanche. Trees a foot in diameter were literally snapped off and shattered into small fragments by the force of the snow slide as it coursed down the mountain plowing a swath hundreds of yards wide.

Some trees were plucked from the ground with most of their roots intact and moved hundreds of yards.

These white birch trees were snaped off a foot above the ground and raked down like grass.

This tree was twisted wildly as the avalanche struck and then ripped apart.

While this large balsam tree was pulled out by the roots.

Looking across the slide track from the Ammonoosuc Ravine Trail (Ammy) 1/2 mile down the mountain from Gem Pool.

Looking up the slide track from the Ammy.

Looking up slope from a little ways higher up on the Ammy.

Liz collects fragments of wood that look as though they were shattered by an explosion.

This is looking up from the vantage point that I took a series of photos throughout the winter looking up the slide track into Ammonoosuc Ravine.

Looking up into the central gully in Ammonoosuc Ravine. It's now possible to see how high up on the mountain that the avalanche started and the path it followed.

Looking up into the central gully from its confluence with the right-hand gully. The debris is scattered as far up the gully as you can see in the fog suggesting that the avalanche started either very high up in Ammonoosuc Ravine or in the snow fields above the ravine.

As we ascended the central gully we found that the snow was badly undercut by the water coursing down and making it dangerous to go up further, but it is clear that at this point, about 2/3 of the way up, the avalanche was already causing heavy damage to vegetation at this height.

This is a balsam root that was shattered by the blast of the avalanche along the side of the gully.

Looking up the right gully. It is difficult to determine exactly the timing of the avalanche, or how it started, but it's likely that the two gullies slid at the same time, or very nearly, and joined forces. Heavy rains probably triggered the slide by saturating the snow making it heavy and viscose and lowering its cohesion with the base layers of snow. The water added density and mass increasing the destructive potential of the avalanche.

High up in right gully with evidence that the slide was stripping trees and other vegetation this high up.

The top of the right gully. Evidence provided by broken limbs and shrubs indicate the avalanche was already moving at full throttle as it came down this part of the gully. Lakes of the Clouds hut is about 1 mile away at this point. We considered bushwhacking in that direction but the rain was turning to snow and the wind was picking up as the temperature dropped and we headed down.

Liz tried, with some success, to 'boot ski' down.

In the woods behind the Cog Railway Base Station I was amazed to find this Red Trillium (Trillium erectum) already producing a flower. With the immediate cool temperatures and all the snow about it seems too early for Trilliums. On the other hand, there have been back-to-back warm days recently as well.

As we came out of the woods near the base station we were greeted by this beautiful, healthy red fox (Vulpes fulva) in the middle of its lunch. We weren't sure but it looked like a baby muskrat it was eating.

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