- Ridge
A ridge is a geological feature that features a continuous elevational crest for some distance. Ridges are usually termed
hill s ormountain s as well, depending on size. There are several main types of ridges:*Dendritic ridge: In a typical plateau terrain, the stream drainage valleys will leave intervening ridges. These are by far the most common ridges. These ridges usually represent slightly harder rock, but not always -- they are often simply because there were larger joint spaces where the valleys formed, or other chance occurrences. This type of ridge is generally somewhat random in orientation, often changing direction frequently, often with knobs at intervals on the ridge top.
*Stratigraphic ridge: In places such as the
Ridge-and-valley Appalachians , very long, very even, very straight ridges are formed due to the fact that they're the uneroded remaining edges of the more resistant strata that were folded laterally. Similar ridges have formed in places such as theBlack Hills , where the ridges form concentric circles around theigneous core. Sometimes these ridges are called "hogback ridges".*Oceanic spreading ridge: In
tectonic spreading zones around the world, such as at theMid-Atlantic Ridge , the volcanic activity forming new plate boundary forms volcanic ridges at the spreading zone. Isostatic settling and erosion gradually reduce the elevations moving away from the zone.*Crater ridges: Large
meteorite strikes typically form largeimpact crater s bordered by circular ridges.*Volcanic caldera ridges: Large
volcano es often leave collapsed centralcaldera s that are bordered by circular ridges.*Thrust fault ridges:
Thrust fault s often formescarpment s. Sometimes the tops of the escarpments form not plateaus, but slope back so that the edges of the escarpments form ridges.*Dune ridges: In areas of large-scale
dune activity, certain types of dunes result insand ridges.*Moraines and eskers: Glacial activity may leave ridges in the form of
moraine s andesker s. An arête is a thin ridge of rock that is formed by glaciers.*Volcanic subglacial ridges: Many
subglacial volcano es create ridge-like formations when lava erupts through a thickglacier orice sheet .ee also
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Tectonic uplift External links
* [http://interridge.org InterRidge] An initiative for international cooperation in ridge-crest studies
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