1. Soil and Topography
Soils at the top and bottom of the slope tend to be thicker than the soil on the slope itself

4. Section 12.4: Erosion
Erosion – the process by which the products of weathering are transported
Most of the eroded soil is deposited elsewhere as transported soil
Accelerated Soil Erosion – unwise farming and ranching practices increase soil erosion
Clearing forests, overgrazing, etc…
Gullying – process of rainwater eroding soil to produce gullies
Sheet Erosion – stripping away of parallel layers of topsoil to expose the surface of subsoil or bedrock

6. Sheet erosion

7. Soil Conservation
Terracing – creation of steplike ridges that follow the contours of the land; prevent rapid erosion
Crop rotation – rotating of crops planted on a yearly basis; stops erosion in its early stages and allows gullies formed during one season to be filled with soil in the next

8. Gravity and Erosion
Gravity causes rock fragments to move down inclines
Movement of fragments down an incline is called mass movement; can either be rapid or slow
Talus – accumulation of fragments at the base of a slope
May be reduced to smaller fragments through mechanical and chemical weathering

9. Mass Movements Rapid Mass Movements Slow Mass Movements
Rockfall: fall of rock from a steep cliff
Landslide: sudden movement of masses of loose rock and soil down the slope of a hill, mountain or cliff
Mudflow: movement of a large mass of mud
Slump: movement of a large piece of soil or rock down a slope in a single piece
Slow Mass Movements
Solifluction: occurs in the mountain and arctic climates where there is permafrost and soil that has thawed above the permafrost and flows down the slope
Solifluction means “soil flow”
Creep: extremely slow downhill movement of rock fragments

10. Rockfall

13. Erosion and Landforms
Landform: physical features on the Earth’s surface
Three major landforms:
Mountains
Plains
Plateaus
Erosion of Mountains
Mountains are generally uplifted faster than they are eroded; mountains being uplifted are rugged with sharp peaks
Peneplain: low almost featureless surface near sea level caused as a result of erosion
New England
Monadnocks: knobs of hard rock (granite) that are resistant to erosion and protrude above the peneplain

15. Erosion of Plains and Plateaus
Plain – flat landform that is generally not high above sea level
Plateau – flat landform, high elevation; subject to more erosion than a plain
Mesa – smaller fragments of a plateau created by erosion
Buttes – smaller fragments of a mesa created by erosion