The principal water inputs to a glacier are the bergschrunds in cirques and crevasse fields lower on the glacier. Subglacial water flows are maintained by high water pressure, rather than by melting of the subglacial channel walls. See Siegert (2005) Ann. Rev. Earth & Plan. Sci. 33 and Boulton et al. (2007) Qly. Sci. Rev. 26, 7–8.
Subjects: Earth Sciences and Geography.