land between tectonic boundaries creating volcanic ridges at the spreading zone. Isostatic settling and erosion gradually reduces the elevations moving away from the zone. Impact Crater ridge Large asteroid strikes typically form large impact craters bordered by rim(s) that are circular ridge(s). Shutter ridge 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. Volcanic and Hydrothermal ridges Pressure ridge (lava) A specific case of pressure ridge, also known as a tumulus, 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. Volcanic crater/caldera ridges Large volcanoes often have a central crater or caldera or both, bordered by rims that form circular ridges. Volcanic subglacial ridges Subglacial volcanic eruptions can create volcanic ridges, known as tindars, that vary from tens of meters up to 250 meters in height. Tindars are a piles of volcanic ash that have been generated by explosive subaqueous eruptions in a glacial meltwater-filled vault or lake within a glacier or ice sheet. See also References Montane ecology Erosion landforms Slope landforms Ridges Oronyms