| A | B |
|---|
| mass movement | Downslope movement of Earth materials, due to gravity that can occur suddenly or very slowly, depending on the weight of the material, its resistance to sliding, and whether a trigger, such as an earthquake, is involved. |
| creep | Slow, steady downhill movement of loose weathered Earth materials, especially soils, causing objects on a slope to tilt. |
| mudflow | Rapidly flowing, often destructive mixture of mud and water that may be triggered by an earthquake, intense rainstorm, or volcanic eruption. |
| landslide | Rapid downslope movement of a mass of loose soil, rock, or debris that has separated from the bedrock; can be triggered by an earthquake. |
| slump | Mass movement that occurs when Earth materials in a landslide rotate and slide along a curved surface, leaving a crescent-shaped scar on a slope. |
| avalanche | Landslide that occurs in a mountainous area when snow falls on an icy crust, becomes heavy, slips off and slides swiftly down a mountainside. |
| deflation | Lowering of land surface caused by wind erosion of loose surface particles, often leaving coarse sediments behind. |
| abrasion | Process of erosion in which wind-blown or waterborne particles, such as sand, scrape against rock surfaces or other materials and wear them away. |
| ventifact | Rock shaped by wind-blown sediments. |
| dune | Pile of wind-blown sand that developes over time, whose shape depends on sand availability, wind velocity and direction, and amount of vegetation present. |
| loess | Thick, wind-blown, fertile deposit of silt that contains high levels of nutrients and minerals. |
| glacier | Large, moving mass of ice that forms near Earth's poles and in mountainous regions at high elevations. |
| valley glacier | Glacier that forms in a valley in a mountainous area and widens V-shaped stream valleys into u-shaped glacial valleys as it moves downslope. |
| continental glacier | Glacier that forms over a broad, continent-sized area of land and usually spreads out from its center. |
| cirque | Deep depression scooped out by a valley glacier. |
| moraine | Ridge of mixed debris deposited by a melting glacier. |
| outwash plain | Area at the leading edge of a glacier, where outwash is deposited by meltwater streams. |
| drumlin | Elongated landform that results when a glacier moves over an older moraine. |
| esker | Long, winding ridge of layered sediments deposited by streams that flow beneath a melting glacier. |
