Mountain and Glacial Landforms

Mountain and glacial landforms include the following:

• areˆte—a thin, almost knifelike, ridge of rock that is typically formed when two glaciers erode parallel U-shaped valleys.

• cirque—an amphitheaterlike valley or valley head, formed at the head of a glacier by erosion.

• crevasse—a huge crack formed by two glaciers colliding.

• dirt cone—a feature of a glacier in which dirt that has fallen into a hollow in the ice forms a coating that insulates the ice below.

• drumlin—an elongated, whale-shaped hill formed by glacial action.

• esker—a long, winding ridge of stratified sand and gravel.

• glacier—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.

• glacier cave—a cave formed within the ice of a glacier.

• glacier foreland—region between the current leading edge of the glacier and the moraines of latest maximum.

• hill—a landform that extends above the surrounding terrain, in a limited area.

• kame—an irregularly shaped hill or mound composed of sand, gravel, and till that accumulates in a depression on a retreating glacier and is then deposited on the land surface with further melting of the glacier.

• kame delta—a glacial landform made by a stream flowing through glacial ice and depositing material upon entering a lake or pond at the end or terminus of the glacier.

• kettle—a shallow, sediment-filled body of water formed by retreating glaciers or draining floodwaters.

• monadnock—an isolated rock hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surround plain.

• moraine—any glacially formed accumulation of unconsolidated glacial debris (soil and rock) that can occur in the currently glaciated and formerly glaciated regions, such as those areas acted upon by a past ice age.

• moulin—a narrow, tubular chute, hole, or crevasse through which water enters a glacier from the surface.

• nunatak—an exposed, often rocky element of a ridge, mountain, or peak not covered with ice or snow within an ice field or glacier.

• outwash fan—a fan-shaped body of sediments deposited by braided streams from a melting glacier.

• pingo—a mound of earth-covered ice found in the Arctic and subarctic that can reach up to 70 meters (230 feet) in height and up to 600 meters (2,000 feet) in diameter.

• pyramidal peak (glacial horn)—a mountaintop that has been modified by the action of ice during glaciation and frost weathering.

• rift valley—linear-shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault.

• sandur—a glacial outwash plain formed of sediments deposited by meltwater at the terminus of a glacier.

• side valley—refers to a valley whose brook or river is confluent to a greater one.

• stream terrace—a relict feature from periods when a stream was flowing at a higher elevation and has downcut to a lower elevation.

• tunnel valley—a deep but narrow valley with a ‘U’-shaped cross-section and frequently a ‘U’-shaped plain that is usually found filled with glacial till.

• valley—a depression with predominant extent in one direction.