It was twisting like a snake down the farther side of the mountain, but, in his experience, slides were as treacherous as serpents.

Bull started hastily for a low cliff that stood up from the floor of the valley, clear of the trees.
He had not gone far when the wind fell away to a whisper, and a dull roaring caught his ear.

He looked back over his shoulder in alarm.

A great wall of white was shooting down the mountainside.

The little slide of surface snow, which had twisted across the surface of the old snows of the winter, had been gaining in weight, in momentum, picking up claws of shrubbery, teeth of stone, and eating through layer after layer of the old snow, packed hard as ice.