Serac

Serac+is+a+block+or+ridge+of+glacial+ice%2C+often+formed+by+intersecting+crevasses+on+a+glacier.

Photo Credit: Photo Via NASA Jet Propulsion Laboratory

Serac is a block or ridge of glacial ice, often formed by intersecting crevasses on a glacier.

Noun.

A pinnacle or ridge of ice on the surface of a glacier.

Among dangers is the notorious weather, cliff exposures, and enormous, high-altitude serac.