Processes that break down rock. Rock is broken apart but not changed chemically.

WeatheringProcesses that break down rock

Weathering affects Earth’s landforms

Mechanical Weathering

Rock is broken apart but not changed chemically

Plant roots, burrowing animals, and expanding ice all weather rock

Chemical Weathering

Minerals in rock dissolve or change to other minerals

“Change!” Natural acids Oxygen

Soil

A mixture of rock Mineral fragments Decayed organic matter Water Air

Humus

Organic matter is slowly changed to humus

Soil moisture

VERY important for plant growth

Soil Profile

The layers are called horizons Most soils have an A, B, & C horizons

Soil Types

We have many different types of soil They have different textures They have different colors Because they are different mixtures

of clay, silt, and sand

Climate

determine the type of soil that forms Based on weathering Moisture, etc

Soil Erosion

A serious problem because topsoil is removed from the land

Erosion can happen rapidly

On steep slopes Areas not covered by vegetation

Preventing Soil Erosion

Plant shelter belts Use no-till farming Plant cover crops after harvesting Contour farming terracing