serac

The smoke found its way out of the holes in the roof as it liked best; and nearly over the fire was a black smoky shelf, supporting several masses of that inferior white cheese, called Serac.

Perhaps the finest part of it [the Lysjoch] is the grand sérac scenery of the Zwillinge Glacier. In August, 1876, a party of four, having missed the right track in crossing this pass when the snow was in very bad condition, were carried down in an avalanche of loose snow probably started by their own weight.