Editing Crevasse (section)

==Description==
[[File:Crevasse-Tangra-Mountains.jpg|thumb|right|A crevasse in [[Tangra Mountains]], Antarctica]]
Crevasses often have vertical or near-vertical walls, which can then melt and create [[serac]]s, [[arch]]es, and other [[Ice|ice formations]].<ref name="Crevasses on Glacier">{{cite journal | title=Crevasses on Glaciers | author=van der Veen, C | journal=[[Polar Geography]] | year=1990 | volume=23 | issue=3 | pages=213–245 | doi=10.1080/10889379909377677}}</ref> These walls sometimes expose layers that represent the glacier's [[stratigraphy]]. Crevasse size often depends upon the amount of liquid water present in the glacier. A crevasse may be as deep as {{convert|45|m|ft|-1}} and as wide as {{convert|20|m|ft|-1}}<ref name=natgeo/>

The presence of water in a crevasse can significantly increase its penetration. Water-filled crevasses may reach the bottom of glaciers or [[ice sheets]] and provide a direct hydrologic connection between the surface,<ref>{{cite journal|author1=Boon, S. |author2=M.J. Sharp |date= 2003|title= The role of hydrologically-driven ice fracture in drainage system evolution on an Arctic glacier|journal=Geophysical Research Letters|volume=30|issue= 18|pages=1916|doi=10.1029/2003gl018034|bibcode=2003GeoRL..30.1916B |s2cid= 133697259|doi-access=free}}</ref> where significant summer melting occurs, and the bed of the glacier, where additional water may moisten and lubricate the bed and accelerate ice flow.<ref>{{cite journal|author1=Zwally, H.J. |author2=Abdalati, W. |author3=Herring, T. |author4=Larson, K. |author5=Saba, J. |author6=Steffen, K. |date=2002|title= Surface melt-induced acceleration of Greenland ice-sheet flow|journal=[[Science (journal)|Science]]|volume=297|issue=5579|pages=218–222|doi=10.1126/science.1072708|pmid=12052902|bibcode=2002Sci...297..218Z |s2cid=37381126|doi-access=free}}</ref><ref name=Colgan>{{cite journal|author1=Colgan, W. |author2=Rajaram, H. |author3=Abdalati, W. |author4=McCutchan, C. |author5=Mottram, R. |author6=Moussavi, M.S. |author7=Grigsby, S. |date=2016|title= Glacier crevasses: Observations, models, and mass balance implications|journal= Rev. Geophys.|volume= 54|issue=1 | doi= 10.1002/2015RG000504|pages= 119–161|bibcode=2016RvGeo..54..119C |doi-access= free}}</ref> Direct drains of water from the top of a glacier, known as [[moulin (geomorphology)|moulin]]s, can also contribute the lubrication and acceleration of ice flow.<ref name=Colgan/>