The
Heap Steep glacier, in Wyoming's Wind River Range. Note the couloirs
harboring permanent snowbanks, but separated from the glacier
by bergschrunds - marginal crevasses at the head of a glacier.
A large extensional crevasse within the glacier is also present.
Also clearly displayed in this picture is the firn line, which separates
the zone of net ablation (melting) year-to-date from the zone of
net accumulation. Firn lines from two previous seasons
are visible, arcing downward near the centerline of the glacier, where
ice flow velocity is the fastest. On the glacier's surface in the
ablation zone are a network of meltwater channels, which reform
from year to year, and areas of surficial debris or meltout till.
Lateral and terminal moraines are also faintly evident at the margins
of the photo, as is a moraine-dammed lake near the bottom.
If the italicized features are not immediately obvious, click on the photo to see an annotated version of the photograph. To compare the two side-by-side, right click this photo to open the annotated photo in a new Web page.