Editing Glacier (section)

=== Classification by thermal state ===
[[File:Ellesmere Island 06.jpg|thumb| Webber Glacier on [[Grant Land]] is an advancing polar glacier]]
Thermally, a ''temperate glacier'' is at a melting point throughout the year, from its surface to its base. The ice of a ''polar glacier'' is always below the freezing threshold from the surface to its base, although the surface [[snowpack]] may experience seasonal melting. A ''subpolar glacier'' includes both temperate and polar ice, depending on the depth beneath the surface and position along the length of the glacier. In a similar way, the thermal regime of a glacier is often described by its basal temperature. A ''cold-based glacier'' is below freezing at the ice-ground interface and is thus frozen to the underlying substrate. A ''warm-based glacier'' is above or at freezing at the interface and is able to slide at this contact.<ref name="ColdBased">{{cite book|title=Encyclopedia of Snow, Ice and Glaciers |first1=Reginald D. |last1=Lorrain|first2=Sean J. |last2=Fitzsimons |editor1-first=Vijay P. |editor1-last=Singh |editor2-first=Pratap |editor2-last=Singh |editor3-first=Umesh K. |editor3-last=Haritashya |publisher=Springer Netherlands |pages=157–161 |doi=10.1007/978-90-481-2642-2_72 |chapter=Cold-Based Glaciers |series=Encyclopedia of Earth Sciences Series |date=2011 |isbn=978-90-481-2641-5}}</ref> This contrast is thought to a large extent to govern the ability of a glacier to effectively [[Glacial erosion|erode its bed]], as sliding ice promotes [[Plucking (glaciation)|plucking]] at rock from the surface below.<ref>[[Geoffrey Boulton|Boulton, G.S.]] [1974] "Processes and patterns of glacial erosion", (In Coates, D.R. ed., ''Glacial Geomorphology''. A Proceedings Volume of the Fifth Annual Geomorphology Symposia Series, held at Binghamton, New York, September 26–28, 1974. Binghamton, NY, State University of New York, pp. 41–87. (Publications in Geomorphology))</ref> Glaciers which are partly cold-based and partly warm-based are known as ''polythermal''.<ref name="ColdBased" />