Editing Mountain (section)

===Fold mountains===
{{Main|Fold mountains}}
[[File:Lewis overthrust fault nh10f.jpg|thumb|Illustration of mountains that developed on a [[fold (geology)|fold]] that has been [[Thrust fault|thrust]]]]
Fold mountains occur when two plates collide: shortening occurs along thrust faults and the crust is overthickened.<ref name="Hatcher">{{Cite book |last=Searle |first=Michael P. |title=4-D framework of continental crust |publisher=Geological Society of America |year=2007 |isbn=978-0-8137-1200-0 |editor-last=Hatcher |editor-first=Robert D., Jr. |editor-link=Robert D. Hatcher |pages=41 ff |chapter=Diagnostic features and processes in the construction and evolution of Oman-, Zagros-, Himalayan-, Karakoram-, and Tibetan type orogenic belts |editor-last2=Carlson |editor-first2=M. P. |editor-last3=McBride |editor-first3=J. H. |editor-last4=Martinez Catalán |editor-first4=J. R. |chapter-url=https://books.google.com/books?id=jD-zXhTfJuMC&pg=PA41}}</ref> Since the less dense [[continental crust]] "floats" on the denser [[Mantle (geology)|mantle]] rocks beneath, the weight of any crustal material forced upward to form hills, [[plateau]]s or mountains must be [[isostasy|balanced by the buoyancy force]] of a much greater volume forced downward into the mantle. Thus the continental crust is normally much thicker under mountains, compared to lower lying areas.<ref>{{Cite book |last=Press |first=Frank |url=https://archive.org/details/earth0004pres/page/413 |title=Earth |last2=Siever |first2=Raymond |publisher=W.H. Freeman |year=1985 |isbn=978-0-7167-1743-0 |edition=4th |page=[https://archive.org/details/earth0004pres/page/413 413]}}</ref> Rock can [[fold (geology)|fold]] either symmetrically or asymmetrically. The upfolds are [[anticline]]s and the downfolds are [[syncline]]s: in asymmetric folding there may also be recumbent and overturned folds. The [[Balkan Mountains]]<ref>{{Cite journal |last=Hsü |first=Kenneth J. |last2=Nachev |first2=Ivan K. |last3=Vuchev |first3=Vassil T. |date=July 1977 |title=Geologic evolution of Bulgaria in light of plate tectonics |journal=Tectonophysics |volume=40 |issue=3–4 |pages=245–256 |bibcode=1977Tectp..40..245H |doi=10.1016/0040-1951(77)90068-3}}</ref> and the [[Jura Mountains]]<ref>{{Cite journal |last=Becker |first=Arnfried |date=June 2000 |title=The Jura Mountains — an active foreland fold-and-thrust belt? |journal=Tectonophysics |volume=321 |issue=4 |pages=381–406 |bibcode=2000Tectp.321..381B |doi=10.1016/S0040-1951(00)00089-5}}</ref> are examples of fold mountains.