Page:The Selkirk mountains (1912).djvu/209

Rh Crevasse—A fissure or crack formed in a snow-field or glacier; caused by non-elasticity of the ice when moving down the uneven surface of its rocky bed. Longitudinal crevasses are formed in the direction of the flow; transverse crevasses, at right angles to the flow.

Diamond Hitch—A technical process of fastening the pack to the pack-saddle, so called from the diamond shape of the rope upon the pack when finished.

Dip—The angles which rock or other strata make with the plane of the horizon. Spoken of in degrees of a vertical circle.

Dirt Bands (Forbes dirt bands)—Dark stripes extending across the surface of a glacier, caused by blown rock-dust collecting in shallow depressions. The depressions are due to open transverse crevasses having joined through pressure from behind. The bands are more or less circular in form, owing to the central ice of the glacier moving more rapidly than the sides.

Divide—The height of land between two drainage basins. The watershed.

Dome—A rounded snow-peak.

Dry Glacier—The lower part of a glacier where it is free from snow.

Fault—A break in a rock-mass by which the strata on one side of the break are depressed so that they are no longer continuous with those on the other side. It may represent displacement of a few inches or of thousands of feet.

Firn—Accumulated snow while in a granular condition and before it has been consolidated into the ice of a glacier; corresponds to the névé or snow-field forming the source of a glacier.

Fohn (German)—A warm wind from a southerly direction.

Forefoot—The part of a dry glacier adjoining the terminal moraine.

Gabel—German for fork; a notch. A deeply cut notch in a ridge.

Gendarme—Name applied to an isolated rock-tower or pinnacle, separated from the mass of which it had originally been a part.

Glacier—The form in which snow accumulating on the higher parts of a mountain range, above snow-line, finds its way down into the valleys. The ice overflows from a firn, or névé or snowfield.

Hanging Glaciers (Glacierettes)—Small glaciers in pockets high on mountain-sides and over-hanging the valley. They frequently nourish trunk-glaciers below. (Vide Mt. Fox, Selkirks.)

Cliff Glaciers (Glacierettes)—Comparatively small glaciers on broad high plateau-like shelves of mountains. They break off in huge pieces falling to the snowfields or trunk-glaciers below. (Vide Mt. Gordon. Rockies.)

Glacier Table—A block of stone, a boulder, supported by a column of ice which its shade has preserved from melting; generally seen on a dry glacier.

Glissade—To slide down a steep snow-slope; performed sitting or standing according to the conditions of the snow. An ice-axe or alpenstock is used for steering.

Grat—An edge or sharp ridge; corresponds to "arête."

Gully—A wide or narrow ravine cleaving the face of a precipice or steep mountain-side—a couloir.