Erosion of Weathered materials Aim: How are weathered materials moved?

I. Erosion Transporting sediments away from their place of origin * The force of gravity drives most forms of erosion.

Examples of Erosion

II. Agents of Erosion Gravity- weathering can weaken a rock on a cliff. The rock is pulled by gravity, causing it to fall to the bottom of the cliff. Mass Movement- the downhill movement of rock or sediment without being carried by water, wind, or ice. Materials can slide, flow, or fall to its resting place. Examples- Avalanche, mud slide, sink hole Mudslide Avalanche Sink Hole

Agents of Erosion Continued B. Running Water- PRIMARY agent of erosion on Earth (streams, rivers, etc. ) 1. Streams can carry sediments in a variety of ways depending on particle size.

Running Water Continued… Solution- dissolved (ex-salt) Flotation- floating on the water’s surface Suspension- smallest particles (colloids) are suspended in the middle of the water. Traction- the largest, heaviest particles are rolled or dragged along the bottom of the stream bed.

Running Water Continued… 2. Erosional Rate- gradient, discharge, and channel shape influence a stream’s velocity and erosion of sediments. a. Sediments transported by stream’s tend to become rounded as a result of abrasion. b. Streams carve v-shaped valleys over the land that they travel on.

V-Shaped Valley

Running Water Continued… 3. Stream Velocity- the faster the stream is moving the heavier the particles (sediments) it can carry-ESRT page 6 a. Gradient- steepness of the slope down which the stream is flowing. Gradient determines a stream’s velocity (speed)

C. Wind It can pick up loose rock materials, such as sand, silt, and clay and carry them away. It usually occurs in areas such as deserts and beaches, where there is little plant life to hold the soil in place.

ESRT Page 6

Recap-Different Kinds of Erosion Erosion Demos