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Transcript of EROSION
1.Define erosion, and list four agents of erosion.
2.Discuss two ways gravity contributes to erosion.
3.Describe the three major landforms shaped by weathering and erosion. erosion:
a process in which the materials of Earth’s surface are loosened, dissolved, or worn away and transported from one place to another by a natural agent: such as
gravity When rock weathers, the resulting rock particles do not always stay near the parent rock.
Various forces may move weathered fragments of rock away from where the weathering occurred.
Gravity and Erosion mass movement:
the movement of a large mass of sediment or a section of land down a slope
Gravity causes rock fragments to move down inclines.
Some mass movements occur rapidly, and others occur very slowly.
Rockfalls and Landslides:
The fall of rock from a steep cliff is called a rockfall.
A rockfall is the fastest kind of mass movement.
When masses of loose rock combined with soil suddenly fall down a slope, the event is called a landslide.
Heavy rainfall, spring thaws, volcanic eruptions, and earthquakes can trigger landslides.
Mudflows and Slumps
The rapid movement of a large amount of mud creates a mudflow.
Mudflows occur in dry, mountainous regions during sudden, heavy rainfall or as a result of volcanic eruptions.
Mud churns and tumbles as it moves down slopes and through valleys, and it frequently spreads out in a large fan shape at the base of the slope.
Sometimes, a large block of soil and rock becomes unstable and moves downhill in one piece.
The block of soil then slides along the curved slope of the surface. This type of movement is called a slump.
Slumping occurs along very steep slopes. Saturation by water and loss of friction within underlying rock causes loose soil to slip downhill over the solid rock.
the slow downhill movement of weathered rock material
Soil creep moves the most soil of all types of mass movements. But creep may go unnoticed unless buildings, fences, or other surface objects move along with the soil.
Erosion and Landforms landforms:
a physical feature of Earth’s surface. There are three major landforms that are shaped by weathering and erosion—
Minor landforms include hills, valleys, and dunes.
All landforms are subject to two opposing processes.
One process bends, breaks and lifts Earth’s crust and thus creates elevated, or uplifted, landforms.
The other process is weathering and erosion, which wears down land surfaces. Erosion of Mountains
During the early stages in the history of a mountain, the mountain undergoes uplift.
When the forces stop uplifting the mountain, weathering and erosion wear down the rugged peaks to rounded peaks and gentle slopes.
Over millions of years, mountains that are not being uplifted become low, featureless surfaces. These areas are called peneplains, which means “almost flat.”
Erosion of Plains and Plateaus
A plain is a relatively flat landform near sea level. A plateau is a broad, flat landform that has a high elevation.
A plateau is subject to much more erosion than a plain.
The effect of weathering and erosion on a plateau depends on the climate and the composition and structure of the rock.