A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for an extended distance. The sides of the ridge slope away from the narrow top on either side. The lines along the crest formed by the highest points, with the terrain dropping down on either side, are called the ridgelines. Ridges are usually termed hills or mountains as well, depending on size.
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.
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 dippingstrata 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".
Oceanic spreading ridge: In tectonic spreading zones around the world, such as at the Mid-Atlantic Ridge, the volcanic activity forms new land between tectonic boundaries creating volcanic ridges at the spreading zone. Isostatic settling and erosion gradually reduces the elevations moving away from the zone.
Shutter ridges: A shutter ridge is a ridge that 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.
Pressure ridges: Also known as a tumuli, usually develops in lava flows especially when slow-moving lava beneath a solidified crust wells upward. The brittle crust usually buckles to accommodate the inflating core of the flow, thus creating a central crack along the length of the tumulus. An ice pressure ridge develops in an ice cover as a result of a stress regime established within the plane of the ice.