Weathering and Soil

Types of WeatheringChemical Weathering: a rock being changed into 1 or more new compoundsOxidation- turns the rock into a rusty colorAcid Rain- Acid in the rain breaks down the rockBiological Activity – acids from plants weather rocksDissolution- when the rock dissolves in a solventCarbonic Acid- deterioration of rock causing it to change color or textureSpheroidal Weathering- water breaks down minerals into a spherical shape.

Mechanical Weathering: the breaking down of a rock, the rock’s mineral composition does not change.

Unloading and Exfoliation- rock breaks off in sheets of layer

Abrasion- the wearing down of rock particles by friction due to water, wind or ice.

Frost Wedging- The process of water freezing and expanding in the cracks of rocks, making the cracks larger

Biological Activity-activities by organisms like animals, plants and humans that cause weathering. (ie burrowing)

Soil

- Weathered rocks that form the top layer of Earth’s surface. There are 3 types- pedalfer, pedocal, and laterite.

Pedalfer Soil Pedocal

Water

Air

Mineral Matter

Organic Matter

Soil Composition

Soil Profile

Horizon A (Topsoil)- Loose and partly decayed organic matter

Horizon B (Subsoil)- Clay transported from C horizon

Horizon C- Partially weathered plant material

Unweathered Plant Material

Soil and Climate

Temperate Climates

• Pedalfer is formed in temperate climates. Pedalfer is found in the Eastern US, mostly in forests.

• Pedalfer is rich in iron, has lots of aluminum rich clays and is brown to red-brown in color.

Desert Climates

• Pedocal is found in dry climates. It can be found in the Western US.• Pedocal is rich in calcite, and calcium carbonate.• Light grey-brown

Humid Tropical Climates

• Laterite soil is formed in humid, hot climates in the tropics. Found in places like Cambodia and Southeast Asia.

• Laterite has lots of iron and aluminum