sults.

Then the lower radio crackled again saying they had just seen a tree go down in the Canyon.  The next minute they excitedly said they saw an enormous mass of snow moving out of the Canyon.  The upper gun crew secured the gun, strapped on skis, and headed for the bottom.

Meanwhile, a wall of snow about 25 feet high crept out of the Canyon toward the base terminal, moving more like a mudslide than an avalanche of snow!  As the snow advanced, ski area personnel began moving everything that could be moved.  A snow cat was hastily driven out of the path of the slowly advancing snow, and others began driving cars out of the parking lot.

The lower terminal of the chairlift was directly in the path of the avalanche.  Dozens of people watched helplessly as the snow crushed the lift control building and slowly twisted and bent the steel support columns of the lift terminal.  The avalanche then threatened the ticket office.  The snow mass crept right to the building, pressed against walls and windows, and stopped without breaking a single pane of glass!

Avalanche Data: This avalanche was classified as HS-AA-5.  It started at an elevation of 3,000 feet and stopped at the 400-foot level, a vertical drop of 2,600 feet. It had run a slope distance of more than 1-1/2 miles.  The fracture line was estimated at 600 feet in length and 2 to 6 feet in depth.  The steepness of the starting zone was 30 degrees.

Most avalanches releasing in the Saddle stop at the transition at Silvertip where the slope gentles to 10 degrees. The unusual feature of this avalanche is that although it slowed and almost stopped when it hit the heavy, wet snow in the lower bowl area, it still had enough force to gouge out the wet snow and set it in motion.  The wet snow then gained enough momentum when it dropped into the Canyon to carry it well past the Canyon mouth.  The wet snow mass was about 25 feet high and 100 feet wide and moved so slowly that those rescuing equipment could keep ahead of the snow with a brisk walk.

Comments: This was the second avalanche of the 1968-69 winter that reached the base area from the Main Bowl (see "Mt. Alyeska Avalanche", 2/21/69).  In the previous 10 years only one other avalanche had released from the Bowl and made it as far as even the Canyon.  To Snow Ranger O'Leary, this pointed out the need for more constant control with the upper gun.  This gun has now been setup for blind firing to prevent dangerous accumulations of new snow from loading the avalanche starting zones during prolonged periods of poor visibility.

An additional safety factor could be had by building a mound field on the transition directly above the Canyon.  These cone-shaped mounds would act to dissipate the force of an avalanche and would retain more snow in this area, keeping it from dropping into the Canyon.