Where does the weathered material go? How does it get there? Ch. 9 – Erosion Where does the weathered material go? How does it get there?

Changing Earth’s Surface Review: What is the difference between weathering and erosion? Weathering: breakdown of rocks and other substances on earth’s surface (destructive) Erosion: movement of weathered material to new places Sediment: pieces of weathered rock

Weathering and Erosion cause CONSTANT, SLOW change on earth’s surface over time, creating a cycle: DEPOSITION Deposition: when sediment gets laid down or dropped (deposited) in new places, it piles up and creates new land forms (constructive process)

But, new landforms are also carved out where rock has weathered and the sediment eroded away (destructive). Slowly, over time, the shape of earth’s surface changes – mountains weather, and the sediment gets eroded, which lowers elevation and makes them less steep – but that sediment piles up somewhere else – creates new landforms where the sediment weathered, and new landforms where the sediment gets eroded to.

So what forces move (erode) the weathered sediment? Gravity – causes mass movement Moving Water Ice Wind Coastal Waves

Sierra Nevada Mountains, CA

Appalachian Mountains, NC

Mass movement; also called mass wasting is when a large mass of weathered sediment moves at the same time, due to force of gravity, the force that pulls things down toward earth’s center; sediment moves downhill

Landslides mixed rock and soil (weathered materials) move downhill quickly; RAPID and DESTRUCTIVE

Mudslides water rapidly accumulates in the ground, such as during heavy rainfall or rapid snow melt, changing the earth into a flowing river of mud as water mixes with loose soil and rocks; moves downhill. Usually occurs in a normally dry area, that all of a sudden gets a huge amount of rain; RAPID and DESTRUCTIVE

Colluvium, San Bernardino Mountains, California

Slump a large mass of soil or other material moves downhill in one large chunk; due to underground weathering; FAST and DESTRUCTIVE.

Creep Slow movement downhill of soil and surface materials results in tree trunks that are curved at the base, tilted utility poles, fence posts, and tombstones; caused mostly by repeated underground freezing and thawing of water; SLOW, and ongoing.

Soil Creep