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Show Following is a tabulation of the March storms J Date March Snowfall Inches Water Content Inches 8 - 1 0 29 33 30 20 1.87 2.52 2.31 1.96 l4 - 15 19 ~ 20 25 Force Critical Critical Critical Critical Wind Direction H & W SW SW SW Notes Coal Pit Argenta In addition there were minor storms on tfre 3rd and 17th. During the period 8-25, when this storm sequence took: place, there were only 3 &ays without snowfall. Coal Pit History: As in the case of Argenta, Coal Pit is a slide path known from early mining days, but no exact dates of earlier occurrence are available. The slide ran March 19* 1948 between 4:00 and 4:30 p.m. during a violent storm. It tore out a large pipeline, crossed the bottom of the canyon and went 200 yards up the opposite side. It buried the highway 20 feet deep for a distance of 300 yards. Some of the trees broken off by this slide were 10 inches in diameter, a measure of the force of the avalanche as well as the time lapse since last occurrence. Terrain data: The accumulation zone and release point of Coal Pit are a complex of steep and narrow gullies overhanging the mouth of Little Cottonwood canyon. The exposure is northwest to northeast. The gullies combine to form a very precipitous chute which issues on to an extensive talus slope. Forest cover is good. The slide path originates on the topmost crags of the canyon and finally funnels into a very narrow chute at the bottom. The difference in elevation is at least 2,000 feet. Weather data: Same as for Argenta with certain exceptions and modifications. Coal Pit ran one v/eek earlier than Argenta, on the third major storm of March instead of the fourth. Coal Pit!s valley elevation is at least 2,000 feet below that of Argenta. A major factor in the production of this slide is that the March storms were very deep, snowfall being about as heavy in the valley as at Alta. The snow type varied, becoming progressively heavier and damper as the elevation decreased. Dumped into the Coal Pit accumulation zone by strong southwest winds, possibly slabbed into the bargain, the sheer weight of the snow was the deciding factor. Normally this snow would have melted or sloughed out piecemeal but the storm sequence was too rapid for this development to take place. Coal Pit at the extreme upper elevation probably started as a dry slide but ended as a typical wet avalanche as shown by the characteristic channeling. In a house about 400 yards down the highway from the slide, its sound was |