Editing Orogeny (section)

===Mountain building===
[[Image:SunRiver.JPG|thumb|250px|An example of [[thin-skinned deformation]] ([[thrust fault]]ing) of the [[Sevier Orogeny]] in [[Montana]]. The white [[Madison Limestone]] is repeated, with one example in the foreground (that pinches out with distance) and another to the upper right corner and top of the picture.]]
[[File:Sierra Nevada Mountains.JPG|thumb|250px|[[Sierra Nevada (U.S.)|Sierra Nevada Mountains]] (a result of [[delamination (geology)|delamination]]) as seen from the [[International Space Station]]]]

[[Mountain formation]] in orogens is largely a result of crustal thickening. The compressive forces produced by plate convergence result in pervasive deformation of the crust of the continental margin ([[thrust tectonics]]).<ref>{{cite journal |last1=Faccenna |first1=Claudio |last2=Becker |first2=Thorsten W. |last3=Holt |first3=Adam F. |last4=Brun |first4=Jean Pierre |title=Mountain building, mantle convection, and supercontinents: revisited |journal=Earth and Planetary Science Letters |date=June 2021 |volume=564 |pages=116905 |doi=10.1016/j.epsl.2021.116905|s2cid=234818905 |doi-access=free }}</ref> This takes the form of folding of the ductile deeper crust and thrust faulting in the upper brittle crust.<ref>{{cite book |last1=Howell |first1=David G. |title=Tectonics of Suspect Terranes |chapter=Mountain building and the shaping of continents |date=1989 |pages=157–199 |doi=10.1007/978-94-009-0827-7_6|isbn=978-94-010-6858-1 }}</ref>

Crustal thickening raises mountains through the principle of [[isostasy]].<ref name= Allen>{{cite book |title= Earth Surface Processes |author= PA Allen |chapter-url= https://books.google.com/books?id=e5i8cRGRCuwC&pg=PA36 |pages= 36 ff |chapter= Isostasy in zones of convergence |isbn= 978-0-632-03507-6 |date= 1997 |publisher= Wiley-Blackwell}}</ref> Isostacy is the balance of the downward [[Newton's law of universal gravitation|gravitational force]] upon an upthrust mountain range (composed of light, [[continental crust]] material) and the buoyant upward forces exerted by the dense underlying [[mantle (geology)|mantle]].<ref name=Wilcock>{{cite book |title= Mechanics in the Earth and Environmental Sciences |chapter= §5.5 Isostasy |page= 170 |chapter-url= https://books.google.com/books?id=K4IgLIDbZicC&pg=PA170|author= Gerard V. Middleton|author2= Peter R. Wilcock |isbn= 978-0-521-44669-3 |date= 1994 |publisher= Cambridge University Press |edition= 2nd}}</ref>

Portions of orogens can also experience uplift as a result of [[Delamination (geology)|delamination of the orogenic lithosphere]], in which an unstable portion of cold [[lithosphere|lithospheric]] root drips down into the asthenospheric mantle, decreasing the density of the lithosphere and causing buoyant uplift.<ref name="delamination_lee">{{cite journal|doi= 10.1126/science.289.5486.1912|pmid= 10988067|title= Osmium Isotopic Evidence for Mesozoic Removal of Lithospheric Mantle Beneath the Sierra Nevada, California|first5= SB|last5= Jacobsen|first4= JT|last4= Chesley|first3= RL|last3= Rudnick|first2= Q|date= 2000|last2= Yin|last1= Lee|first1= C.-T.|journal= Science|volume= 289|issue= 5486|pages= 1912–16|url= http://www.geol.umd.edu/~rudnick/Webpage/Lee_2000_Science.pdf|bibcode= 2000Sci...289.1912L|url-status= dead|archive-url= https://web.archive.org/web/20110615170551/http://www.geol.umd.edu/~rudnick/Webpage/Lee_2000_Science.pdf|archive-date= 15 June 2011}}</ref> An example is the [[Sierra Nevada (U.S.)|Sierra Nevada]] in California. This range of [[fault-block mountain]]s<ref name=Gerrard>{{cite book |title= Mountain Environments: An Examination of the Physical Geography of Mountains |author= John Gerrard |page= 9 |url= https://books.google.com/books?id=jHnrVEyMhkQC&pg=PA9 |isbn= 978-0-262-07128-4 |date= 1990|publisher= MIT Press}}</ref> experienced renewed uplift and abundant magmatism after a delamination of the orogenic root beneath them.<ref name="delamination_lee" /><ref>{{cite journal|doi= 10.1130/0091-7613(2000)28<811:TOVITS>2.0.CO;2|date= 2000|volume= 28|page= 811|title= Timing of Volcanism in the Sierra Nevada of California: Evidence for Pliocene Delamination of the Batholithic Root?|first3= G. Lang|last3= Farmer|first2= Allen F.|last2= Glazner|author= Manley, Curtis R.|journal= Geology|issue= 9|bibcode = 2000Geo....28..811M }}</ref>

[[File:Mount Rundle, Banff, Canada (200544945).jpg|thumb|[[Mount Rundle]], [[Banff, Alberta]]]]

[[Mount Rundle]] on the [[Trans-Canada Highway]] between [[Banff, Alberta|Banff]] and [[Canmore, Alberta|Canmore]] provides a classic example of a mountain cut in dipping-layered rocks. Millions of years ago a collision caused an orogeny, forcing horizontal layers of an ancient ocean crust to be thrust up at an angle of 50–60°. That left Rundle with one sweeping, tree-lined smooth face, and one sharp, steep face where the edge of the uplifted layers are exposed.<ref>{{cite web
|url= http://www.mountainnature.com/geology/platetectonics.htm
|title= The Formation of the Rocky Mountains
|work= Mountains in Nature
|date= n.d.
|access-date= 29 January 2014
|archive-date= 23 July 2014
|archive-url= https://web.archive.org/web/20140723230042/http://www.mountainnature.com/Geology/platetectonics.htm
|url-status= dead
}}</ref>

Although mountain building mostly takes place in orogens, a number of secondary mechanisms are capable of producing substantial mountain ranges.<ref name=Huggett>{{cite book |title= Fundamentals of Geomorphology |author= Richard J. Huggett |url= https://books.google.com/books?id=QY3-bBTUmKEC&pg=PA104 |page= 104 |isbn= 978-0-415-39084-2 |date= 2007 |publisher= Routledge |edition= 2nd}}</ref><ref name=Einsele>{{cite book |title= Sedimentary Basins: Evolution, Facies, and Sediment Budget |url= https://books.google.com/books?id=-N3nidyNoJUC&pg=PA453 |page= 453 |quote= Without denudation, even relatively low uplift rates as characteristic of epeirogenetic movements (''e.g.'' 20m/MA) would generate highly elevated regions in geological time periods. |author= Gerhard Einsele |isbn= 978-3-540-66193-1 |date= 2000 |edition= 2nd |publisher= Springer}}</ref><ref name=Douglas>{{cite book |title= Companion Encyclopedia of Geography: The Environment and Humankind |url= https://books.google.com/books?id=afH8DDAVkUQC&pg=PA33 |page= 33 |author= Ian Douglas |author2= Richard John Huggett |author3= Mike Robinson |isbn= 978-0-415-27750-1 |date= 2002 |publisher= Taylor & Francis}}</ref> Areas that are rifting apart, such as [[mid-ocean ridge]]s and the [[East African Rift]], have mountains due to thermal buoyancy related to the hot mantle underneath them; this thermal buoyancy is known as [[dynamic topography]]. In [[strike-slip]] orogens, such as the [[San Andreas Fault]], [[Thrust tectonics#Restraining bends on strike-slip faults|restraining bends]] result in regions of localized crustal shortening and mountain building without a plate-margin-wide orogeny. [[Hotspot (geology)|Hotspot]] volcanism results in the formation of isolated mountains and mountain chains that look as if they are not necessarily on present tectonic-plate boundaries, but they are essentially the product of plate tectonism. Likewise, uplift and erosion related to [[Epeirogenic movement|epeirogenesis]] (large-scale vertical motions of portions of continents without much associated folding, metamorphism, or deformation)<ref name=Holmes>{{cite book |title= Holmes Principles of Physical Geology |author= Arthur Holmes |author-link= Arthur Holmes|author2= Doris L. Holmes|author-link2 = Doris L. Holmes|url= https://books.google.com/books?id=E6vknq9SfIIC&pg=PT109 |page= 92 |isbn= 978-0-7487-4381-0 |edition= 4th |publisher= Taylor & Francis |date= 2004}}</ref> can create local topographic highs.