Editing Valley (section)

===Hanging tributary{{anchor|Hanging_valleys}}===
[[File:Closeup of Bridalveil Fall seen from Tunnel View in Yosemite NP.JPG|thumb|upright|Bridal Veil Falls in [[Yosemite National Park]] flowing from a hanging valley]]
[[File:Ибърско езеро.jpg|thumb|Hanging valley, [[Ibar (lake)]] valley, [[Rila]] Mountain, [[Bulgaria]]]]

A hanging valley is a [[tributary]] valley that is higher than the main valley. They are most commonly associated with U-shaped valleys, where a tributary glacier flows into a glacier of larger volume. The main glacier erodes a deep U-shaped valley with nearly vertical sides, while the tributary glacier, with a smaller volume of ice, makes a shallower U-shaped valley. Since the surfaces of the glaciers were originally at the same [[elevation]], the shallower valley appears to be 'hanging' above the main valley. Often, waterfalls form at or near the outlet of the upper valley.<ref>{{cite web| title =Glossary of Glacier Terminology| publisher =U.S. Geological Survey| date =May 28, 2004| url =http://pubs.usgs.gov/of/2004/1216/h/h.html| access-date = 2007-05-24 }}</ref>

Hanging valleys also occur in [[fjord]] systems underwater. The branches of [[Sognefjord]] are much shallower than the main fjord. The mouth of [[Fjærlandsfjord]] is about {{Convert|400|m|sp=us}} deep while the main fjord nearby is {{Convert|1200|m|sp=us}} deep. The mouth of [[Ikjefjord]] is only {{Convert|50|m|sp=us}} deep while the main fjord is around {{Convert|1300|m|sp=us}} at the same point.<ref>Nesje, A., & Whillans, I. M. (1994). Erosion of Sognefjord, Norway. ''Geomorphology'', 9(1), 33-45.</ref>

Glaciated terrain is not the only site of hanging streams and valleys. Hanging valleys are also simply the product of varying rates of erosion of the main valley and the tributary valleys. The varying rates of erosion are associated with the composition of the adjacent rocks in the different valley locations. The tributary valleys are eroded and deepened by glaciers or erosion at a slower rate than that of the main valley floor; thus the difference in the two valleys' depth increases over time. The tributary valley, composed of more resistant rock, then hangs over the main valley.<ref>{{cite web|url=http://www4.uwsp.edu/geo/faculty/lemke/alpine_glacial_glossary/landforms/hangingvalley.html |title=Illustrated Glossary of Alpine Glacial Landforms - Hanging Valley |publisher=.uwsp.edu |access-date=2011-10-03}}</ref>