<P> The contours formed by a ridge are long, narrow and elliptical in shape </P> <P> There are several main types of ridges: </P> <Ul> <Li> Dendritic ridge: In typical dissected plateau terrain, the stream drainage valleys will leave intervening ridges . These are by far the most common ridges . These ridges usually represent slightly more erosion resistant rock, but not always--they often remain because there were more joints 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 . </Li> <Li> Stratigraphic ridge: In places such as the Ridge - and - Valley Appalachians, long, even, straight ridges are formed because they are the uneroded remaining edges of the more resistant dipping strata that were folded laterally . Similar ridges have formed in places such as the Black Hills, where the ridges form concentric circles around the igneous core . Sometimes these ridges are called "hogback ridges". </Li> <Li> Oceanic spreading ridge: In tectonic spreading zones around the world, such as at the Mid-Atlantic Ridge, the volcanic activity forming new plate boundary forms volcanic ridges at the spreading zone . Isostatic settling and erosion gradually reduces the elevations moving away from the zone . </Li> <Li> Crater ridges: Large meteorite strikes typically form large impact craters bordered by circular ridges . </Li> <Li> Volcanic crater / caldera ridges: Large volcanoes often leave behind a central crater / caldera bordered by circular ridges . </Li> <Li> Fault ridges: Faults often form escarpments . Sometimes the tops of the escarpments form not plateaus but slope back so that the edges of the escarpments form ridges . </Li> <Li> Dune ridges: In areas of large - scale dune activity, certain types of dunes result in sand ridges . </Li> <Li> Moraines and eskers: Glacial activity may leave ridges in the form of moraines and eskers . An arête is a thin ridge of rock that is formed by glacial erosion . </Li> <Li> Volcanic subglacial ridges: Many subglacial volcanoes create ridge - like formations when lava erupts through a thick glacier or ice sheet . </Li> <Li> Shutter ridges: A shutter ridge is a ridge which has moved along a fault line, blocking or diverting drainage . Typically, a shutter ridge creates a valley corresponding to the alignment of the fault that produces it . </Li> </Ul> <Li> Dendritic ridge: In typical dissected plateau terrain, the stream drainage valleys will leave intervening ridges . These are by far the most common ridges . These ridges usually represent slightly more erosion resistant rock, but not always--they often remain because there were more joints 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 . </Li>

What is another name for a sharp mountain ridge
find me the text answering this question