What is the shape of a glacier?

Brewster Glacier, Westcoast, New Zealand.

Brewster Glacier, Westcoast, New Zealand.

Glaciers come in many shapes and size, but let’s focus on mountain/valley glaciers.  Mountain glacier lengths can vary from 1 kilometer to 100s of kilometers and their thickness can be 50 m to 1000 m.  But there are some similarities between glaciers of different sizes.

  1. These glaciers usually flow from high elevation down to lower elevations
  2. These glaciers have two zones: an accumulation zone at higher elevations (where the amount of snow added in a year is greater than the amount of melt in a year) and an ablation zone at lower elevations (where melt is greater than snowfall).
  3. Many glaciers show a similar area ratio between these zones: 2:1 for accumulation area:ablation area, meaning the area of the glacier that keeps snow even through the summer is twice as large as the melt area. Glaciologists refer to this as the Accumulation Area Ratio (AAR).

The shape of a glacier from a bird’s eye view really depends on the valley shape, have a look on Google Earth for some glaciers, you’ll see what I mean.

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