SCIENCE CHAPTER 2 REVIEW

THE MAIN IDEAS BY: TREVOR KRAFT AND HANA KEIL

The Rock Cycle

The Rock Cycle is a group of changes. Igneous rock can change into sedimentary rock or into metamorphic rock. Sedimentary rock can change into metamorphic rock or into igneous rock. Metamorphic rock can change into igneous or sedimentary rock.

3 Different Types Of Rock

Mechanical And Chemical Weathering

Mechanical Weathering

Mechanical Weathering is the process of breaking large rocks into little rocks. Mechanical Weathering has five causes including freezing and thawing, release of pressure, plant growth, actions of animals, and abrasion. The way that the rocks break down is by weathering. Weathering is the breaking down of rock, soil, and minerals.

Chemical Weathering

Chemical weathering also known as decomposition or decay is the breakdown of rock weathering by chemical mechanisms, the most important ones being carbonation, hydration, hydrolysis, oxidation, and ion exchange in solution.

SOIL

Soil Composition

Soil is a mixture of rock particles, minerals, decayed, organic material, water, and air. Humus helps create spaces in soil for the air and water that plants must have.

Conserve Soil

To improve water quality. All forms of life need clean water to survive. Agricultural and urban soil erosion are major sources of sedimentation and contamination of water supplies. To improve wildlife habitat.

LAYERS OF SOIL

Soil is composed of 5 distinct layers

Humus

Humus usually refers to the natural decay of material such as leaves in the soil's top layer. Humus is dark, organic material that forms in soil when plant and animal matter decays. When plants drop leaves, twigs, and other material to the ground, it piles up.

TopSoil (A Horizon)

The top layer of soil. Often rich in humus and minerals.

Subsoil (B Horizon)

Subsoil is the layer of soil under the topsoil on the surface of the ground. Like topsoil it is composed of a variable mixture of small particles such as sand, silt and/or clay, but it lacks the organic matter and humus content of topsoil.

Weathered Rock Fragments (C Horizon)

Little or no plant or animal life.

Bedrock (D Horizon)

Solid rock underlying loose deposits such as soil or alluvium.

THE END

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