Ridge

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• 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
  Ridge-and-valley Appalachians
  
  The Ridge-and-Valley Appalachians, also called the Ridge and Valley Province or the Valley and Ridge Appalachians, are a Physiographic regions of the world of the larger Appalachian Mountains division and are also a belt within the Appalachian Mountains extending from northern New Jersey westward into Pennsylvania and southward...
  , very long, very even, very straight ridges are formed because they are the uneroded remaining edges of the more resistant strata that were folded laterally. Similar ridges have formed in places such as the Black Hills
  Black Hills
  
  The Black Hills are a small, isolated mountain range rising from the Great Plains of North America in western South Dakota and extending into Wyoming, United States....
  , where the ridges form concentric circles around the igneous core. Sometimes these ridges are called "hogback ridges".

• Oceanic spreading ridge: In tectonic spreading zones around the world, such as at the Mid-Atlantic Ridge
  Mid-Atlantic Ridge
  
  The Mid-Atlantic Ridge is a mid-ocean ridge, a divergent tectonics plate boundary located along the floor of the Atlantic Ocean, and the longest mountain range in the world....
  , 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
  Meteorite
  
  A meteorite is a natural object originating in outer space that survives an impact with the Earth's surface. While in space it is called a meteoroid....
   strikes typically form large impact crater
  Impact crater
  
  In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with larger body....
  s bordered by circular ridges.

• Volcanic caldera ridges: Large volcano
  Volcano
  
  A volcano is an opening, or rupture, in a planet's surface or Crust , which allows hot, molten rock, ash, and gases to escape from below the surface....
  es often leave collapsed central caldera
  Caldera
  
  A caldera is a cauldron-like volcano feature usually formed by the collapse of land following a volcanic eruption such as the one at Yellowstone National Park....
  s that are bordered by circular ridges.

• Thrust fault ridges: Thrust fault
  Thrust fault
  
  A thrust fault is a type of Geologic fault, or break in the Earth's crust with resulting movement of each side against the other, in which a lower stratigraphic position is pushed up and over another....
  s often form escarpment
  Escarpment
  
  In geomorphology, an escarpment is a transition zone between different physiogeographic provinces that involves a sharp, steep elevation differential, characterized by a cliff or steep slope....
  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
  Dune
  
  In physical geography, a dune is a hill of sand built by aeolian processes. Dunes are subject to different forms and sizes based on their interaction with the wind....
   activity, certain types of dunes result in sand
  Sand
  
  Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.As the term is used by geologists, sand particles range in diameter from 0.0625 to 2 millimeters....
   ridges.

• Moraines and eskers: Glacial
  Glacier
  
  A glacier is a large, slow-moving mass of ice, formed from compacted layers of snow, that slowly deforms and flows in response to gravity and high pressure....
   activity may leave ridges in the form of moraine
  Moraine
  
  A moraine is any glacially formed accumulation of unconsolidated glacial debris which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past ice age....
  s and esker
  Esker
  
  An esker is a long, winding ridge of stratified sand and gravel, examples of which occur in glacier and formerly glaciated regions of Europe and North America....
  s. An arête is a thin ridge of rock that is formed by glaciers.

• Volcanic subglacial ridges: Many subglacial volcano
  Subglacial volcano
  
  A subglacial volcano is a volcanic form produced by subglacial eruptions or eruptions beneath the surface of a glacier or ice sheet which is then melted into a lake by the rising lava....
  es create ridgelike formations when lava erupts through a thick glacier
  Glacier
  
  A glacier is a large, slow-moving mass of ice, formed from compacted layers of snow, that slowly deforms and flows in response to gravity and high pressure....
   or ice sheet
  Ice sheet
  
  An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 square kilometer . The only current ice sheets are in Antarctica and Greenland; during the last glacial period at Last Glacial Maximum the Laurentide ice sheet covered much of Canada and North America, the Wisconsin glaciation ice sheet covered n...
  .

See also

• Tectonic uplift
  Tectonic uplift
  
  Tectonic uplift is a geology process most often caused by plate tectonics which increases elevation. The opposite of uplift is subsidence, which results in a decrease in elevation....
  

External links

• An initiative for international cooperation in ridge-crest studies