Rainier is our newest and most ambitious project. The East Crater glacier is actually a trapped ice plug that doesn't flow over the crater rim—the ice stays contained within its crater. By contrast, the West Crater ice cap flows over its crater edge and feeds some of the glaciers high up on the mountain. Both ice caps seem to be in an approximate state of balance - the amount of snow that accumulates annually roughly equals the amount of melting from geothermal heating on the crater floor.
The value of studying a 'balanced' glacier is that a scale in balance is easily tipped one way or the other. This glacier cave scenario lets us detect even subtle changes in climate or the geothermal output of the mountain.
For more information, view the National Geographic web article and video:
National Geographic's Expedition Raw