Rocks in high places, like mountains, are broken by weathering. Then, the sediments are carried down the mountain to lower lands by erosion. When erosion slows down in flat, low areas, the sediments are deposited.

​

​Rocks move from high places to low places.

​1. Weathering breaks rocks on mountains (high areas)
2. Erosion moves the sediments downslope.
3. Deposition makes collections of sediment into landforms in low areas.

Weathering - breaking down rock

1.Chemical Weathering

Chemical weathering changes the minerals in a rock to new substances by a chemical reaction. They cannot change back.
We can see this as a color change, a change in hardness, or the addition/loss of certain minerals from the rock.
Ex: oxidation (oxygen), dissolution, acid weathering, hydrolysis (water)

Oxidation:
The metal reacts with oxygen in air and water. It changes color.
Ex: iron changes from gray to red-brown rust

​Chemical Weathering

Weathering - breaking down rock

2.Mechanical Weathering

Mechanical weathering simply breaks the rock into smaller pieces. The rocks will change size and shape. The minerals in the rock stay the same.

Ex: frost wedging, root wedging, exfoliation, abrasion

​Abrasion:
small moving particles break down the surfaces of rocks they hit

​Mechanical Weathering

Erosion usually happens at high elevations and on steep slopes.

Rocks are picked up and carried away by water, wind, ice, and gravity. The more energy, the more rocks are eroded.
Erosion leaves sharp-looking solid rock surfaces. They look carved.

Erosion

After weathering....

Deposition usually occurs in flat and low areas, like deltas.

When erosion slows and weakens, sediments stop moving and pile up (accumulate). This makes collections of sediments.

Deposition

After erosion...