Blue glacier is a valley glacier—it carries snow and ice that accumulates on Mount Olympus down a valley to a lower elevation where it then melts. This glacier follows a pre-existing stream valley and is confined by slopes on either side. Most valley glaciers are temperate or warm glaciers, meaning that the ice is at or near the melting point. Glaciers can also take the form of an ice sheet or cap such as in Antarctica. Most of the Antarctic ice cap is a cold polar glacier where the temperature is well below the melting point.
THE LOWER BLUE GLACIER
BLUE GLACIER FROM THE AIR LOOKING SOUTH
Where’s the chicken? The top of a valley glacier is known as the head, the bottom may be referred to as the tip, snout or terminus. Three terms that help identify where something is on a glacier are subglacial—beneath the ice, englacial—within the ice, and supraglacial—on the surface of the ice. Other locations are mapped on the photograph above.
An icefall forms when the glacier flows rapidly over a steep or vertical portion of the valley. The chaotic jumble of crevasses and seracs in an icefall creates complex patterns in the structure of the glacier below it.

A serac is a large, isolated, and often unstable block of ice formed where the glacier surface is severely fractured. Seracs are common in the icefall and one of the reasons climbers avoid the area.

THE ICEFALL
A crevasse is an open fissure in the glacier surface. Crevasses open slowly from the stress of glacier flow and provide a unique window through which one can see the inside structure of a glacier. Crevasses ranging from one to 30 meters deep can be found throughout Blue Glacier.
A CREVASSE
The bergschrund is a crevasse that separates the stagnant ice attached to the rock at the head of a glacier from the flowing ice. Though often disguised by snow, the feature is usually permanent. This bergschrund at the head of Blue Glacier is visible as a series of parallel crevasses below the summit arete. If all the snow was removed and the ice exposed, the crevasses would form a single gaping crack. The bergschrund often creates a challenge for late season mountaineers, as they have to cross it to reach summit rock.

A cirque is a semi-circular glacier carved basin near the head of the glacier. The three summit peaks of Mount Olympus ring a cirque carved out by the Blue Glacier.

THE BERGSCHRUND IN THE CIRQUE
A sharp narrow ridge eroded from both sides is known as an arete. The three summits of Mt Olympus, West, Middle, and East are on an arete that separates the Blue from the Hoh Glacier.

An open U-shaped pass in a ridge is known as a col. Formed by glacial erosion working on both sides, the col links the Blue with the Hoh Glacier. Climbers pass through this saddle in the arete to reach Mount Olympus’ East Peak.

THE COL AND LOWER SHOULDER OF AN ARETE
The Blue Glacier’s terminus is currently divided 100 meters above the tip. A large rocky buttress has split the flow of ice into two smaller termini since the early 1900’s; previously the ice was deep enough to flow over it. Glacier Creek begins at the snout of the glacier and joins the larger Hoh River that eventually flows into the Pacific Ocean 55 kilometers downstream.
BLUE GLACIER'S TERMINUS

ACCUMULATION>

intro | terminology | accumulation | firn | blue | ablation | water | equilibrium | massbalance | movement | crevasse | structure | algae | moraine | debris | erosion
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Benjamin Drummond 2002