| Term | Definition |
| erosion | The process by which water, ice, wind, or gravity moves weathered rock and soil. |
| sediment | Earth materials deposited by erosion |
| deposition | Process in which sediment is laid down in new locations |
| mass movement | Any one of several processes by which gravity moves sediment downhill |
| landslide | The most destructive kind of mass movement. This occurs when rock and soil slide quickly down a steep slope. |
| mudflow | This type of mass movement is the rapid downhill movement of a mixture of water, rock and soil. |
| slump | In this type of mass movement a mass of rock and soil suddenly slips down a slop. |
| creep | This type of mass movement is the very slow downhill movement of rock and soil. |