Rocks, Weathering, and Soil Information

The Effects of Weathering All exposed rock is in the path of weathering and erosion. Weathering is the process that breaks down rock and other substances at the Earth’s surface. Heat, cold, water, ice, carbon dioxide, oxygen etc.. all contribute to weathering.

Weathering and Erosion Weathering examples: Repeated freezing and thawing. Rainwater dissolving minerals. Erosion is the movement of rock particles by wind water, ice, or gravity. Weathering and erosion work together to carry away the rocks at the surface. There are two types of weathering: Mechanical Weathering Chemical Weathering

1. Mechanical Weathering Mechanical Weathering: rock is physically broken into smaller pieces that have the same chemical composition as the rock they came from. Examples: freezing and thawing, release of pressure, growth of plants, actions of animals, and abrasion (grinding away of rock by particles in the wind and water).

2. Chemical Weathering Chemical Weathering: the process that breaks down rock through chemical changes and produces rock particles that have a different mineral makeup from the rock they came from. Examples: Hot or soft spots in rock Water Oxygen Carbon Dioxide Living organisms Acid Rain

Soil Formation Over many years, weathering and erosion will cause the formation of soil. Soil is the loose, weathered material on the Earth’s surface in which plants can grow Soil forms as rock is broken down by weathering and mixes with other materials on the surface.

Soil Composition Soil is a mixture of rock particles, minerals, decayed organic material, air, and water.

Soil Composition and Texture The decayed organic material in the soil is humus. Humus is a dark-colored substance that forms as plant and animal remains decay. Soil texture depends on the size of soil particles. Sand Silt Clay Big small

Life in Soil Organisms mix the soil and make spaces for air and water. Other soil organisms make humus, the material that makes soil fertile.

With and Without Worms 

Soil Conservation Soil is one of Earth’s most valuable resources because everything that lives on the land depends directly on indirectly on soil. Fertile soil is valuable because there is a limited supply. Less than 1/8th of the land on Earth has soils well suited for farming.

The Dust Bowl In the 1930s plowing removed the grass form the Great Plains and exposed the soil. In times of drought, the topsoil quickly dried out, turned to dust, and blew away. This event helped people appreciate the value of soil. Check It Out!!

Soil Lost To The Seas!!

Exit Slip Write a paragraph that describes the importance of soil and how it is made