What shapes the Earth

Weathering, Erosion, and Deposition are processes that act together to wear down and build up the Earth's surface. These processes have occurred over billions of years.​

What is weathering?

• Weathering is a process that BREAKS DOWN rocks and creates sediments.

• Sediments refer to small pieces of rocks​.

• Two types of weathering: Chemical and Mechanical (physical)​.

Chemical Weathering

• Chemical weathering is the decomposition of rock caused by chemical reactions. This creates new compounds.

• Agents of chemical weathering: water, oxygen, acid, and organisms

Mechanical Weathering

• Mechanical weathering is the process of breaking BIG rocks into little ones without changing the chemical composition of a rock.

• ​The most common type of mechanical weathering is the constant freezing, and thawing of water.

• As water freezes, it expands, becoming about 10% larger than it was in liquid form.

• Temperature changes also affect mechanical weathering. As temperatures heat up, the rocks expand.

• As the temperatures cool down, rocks contract.

Erosion

Erosion: natural forces MOVE rock and soil to another place.

Natural forces such as gravity, running water, glaciers, waves and wind cause erosion.​

Weathering is the breaking down of rocks while erosion is the process of moving those pieces.

Deposition

Deposition: occurs when sediment is LAID DOWN.

So Erosion moves and deposition lays it down somewhere else.

Examples of Physical Weathering

​Ice Wedging:  when liquid water goes into cracks and then freezes causing the cracks to get wider
Wind: blowing sand grinds pieces of rock off larger rocks like sandpaper. This is called Abrasion
Flowing Water:  
Moves rocks and soil as it goes

The strongest weathering force

Examples of Physical Weathering Continued

​Plant Roots:  growing into cracks in the rock, slowly breaking them apart.

Animals: burrow in the ground, break up soil, and loosen rocks to be exposed to further weathering.

Examples of Chemical weathering

Air
Oxidation: a chemical reaction in which oxygen combines with an element such as iron to form an oxide (rust)

Acid Rain
Rain, Sleet, or Snow that contain high concentrations of Acids

Factors that effect Weathering

Surface Area: the more rock is exposed to weathering the faster the rock will be worn down.

Temperature: areas with drastic temperature changes have rapid mechanical weathering (ex. seasonal)
Climate: warm and humid areas have faster chemical weathering (ex. tropical)
Type of Rock: minerals in rock determine how quickly weathering will take place