Post 24590
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Landslides, large and small, often plunge into these lakes. One of the largest rock avalanches that I ever saw made one wild leap into Chasm Lake and buried itself. This was about the middle of June. This glacier lake is on the eastern side of Long’s Peak and is in a most utterly wild place. The lake was still covered with thick ice, and on the ice the snow lay deep. But spring was melting and loosening things in the alpine heights. As I stood on a talus slope above the outlet of the lake, an echoing on the opposite cliffs told me that a rock-slide was coming down. Almost instantly there was the ripping whizz of falling stone. A huge stone struck and pierced twenty feet of snow and more than four feet of ice, which covered the lake. At the same instant there came sounds of riot from above. More stones were coming down. The crash of their striking, repeated and reëchoed by surrounding cliffs and steeps, made an uproarious crashing as though the top of Long’s Peak had collapsed. It was an avalanche of several thousand tons off the slope of Mt. Washington.
This avalanche was formed of a quantity of broken granite sufficient to load a number of freight-trains. It smashed through the icy cover of the lake. The effect was like a terrific explosion. Enormous fragments of ice were thrown into the air and hurled afar. Great masses of water burst explosively upward, as if the entire filling of water had been blown out or had leaped out of its basin. The cliffs opposite were deluged. The confused wind-current which this created shredded and separated much of the water into spray, dashing and blowing it about. I was thoroughly drenched. For half a minute this spray whirled so thickly that it was almost smothering.
Water and ice are incessantly at work tearing down the heights. Water undermines by washing away the softer parts and by leaching. Every winter ice thrusts its expansive wedge into each opening. Places are so shattered by this explosive action that thousands of gallons of water are admitted. This collects in openings, and the following winter the freezing and forcing continues. During the winter the irresistible expansion of freezing water thus pushes the rocks and widens the openings with a force that is slow but powerful. Winter by winter rocks are moved; summer by summer the water helps enlarge the opening. Years or centuries go by, and at last during a rainy time or in the spring thaw a mass slips away or falls over. This may amount to only a few pounds, or it may be a cliff or even a mountain-side.