Kimia's+Notes+Chapter+3+Section+1


 * __Changing Earth's Surface__**

Key Terms: Erosion-the process by which water,ice,and wind,or gravity moves weathered rock or soil. Sediment-small,solid pieces of material from rocks or organisms. Depostion-the process in which sediment is laid down in new locations Gravity-a force that moves rocks and other material downhill.

Wearing Down and Building Up- A mudflow is a spectacular example of erosion.A mudlfow is a very rapid type of erosion.Other types of erosion moe soil and rock more slowly.Gravity,running water,glaicers,waves,and wind are all causes of erosion.The material moed by erosion is sediment.Both weathering and erosion produce sediment.Deposition changes the shape of the land.Weathering,erosion,and depsotion act together in a cycle that wears down and builds up earth's surface.As a mountain wears down in one place,new landforms build up in other places.

Mass Movements-Graity causes**mass movement**,any one several processes that moe sediment downhill.The different types of mass movement include landslides,mudflows,slump,and creep.Mass movements can be rapid or slow. Landslides-A landslide is kind of mass movement that occurs when rock and soil slide rapidly down a steep slope.Some landslides contain huge masses of rock.But many landslides contain a small amount of rock and soil. Mudflows-A mudflow is the rapid downhill movement of a mixture of water,rock,and soil.The amount of water in mudlfow can be as hgigh as 60%.Mudflows occur after heavy rains in a normally dry area.In clay soils with a high water content,mudflows may occur even on very gentle slopes. Slump-Unlike a landslide,the material in a slump moves down in one large mass.A slump often occurs when water soaks the bottom of soil that is rich in clay. Creep-Creep is a very slow downhill movement of rock and soil.It can occur on gentle slopes.Creep often results from the freezing and thawing of water in cracked layes of rock beneath the soil.You can see the effects of creep in objects such as telephone poles,gravestones,and fenceposts.