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ensure accuracy. A Science Strategy for the Exploration of
Europa drainage channels within the glacier. The glacier itself
may be several hundreds of meters thick; its structure may be
further complicated by the presence of medial moraines, composed
of rocky debris that snake across many valley glaciers. The
moraine patterns are good indicators of past dynamical
instabilities. Extensive geophysical studies have been conducted
on temperate glaciers in the Pacific Northwest such as the Blue
and Columbia Glaciers. The Bering and Malaspina Glaciers,
located along the Gulf of Alaska, are examples of surging
glaciers with highly crevassed surfaces, complex subglacial
hydrology, and surface and internal moraines. Each has been
intensively studied with surface, airborne, and spaceborne
remote-sensing techniques. Polar Ice Sheets Greenlan