What is weathering? Breaking down of rocks & other materials on Earth’s surface

Rate of Weathering Factors Affecting Rate of Weathering Climate Faster in hot, wet climates Surface Area Faster with small pieces Rock Composition Faster with minerals in limestone, iron Chemical Reactions Faster with certain chemicals

How does weathering affect soil? Weathering causes bedrock to break down and become an ingredient in soil.

What is soil? Soil: mixture that includes silt, sand, & clay

Soil is not DIRT! Dirt is what you track in on your mother's floor, soil is what plants grow in. A scientist would not use the word "dirt" for the surface layer of the ground where plants grow, that is "soil."

Bedrock: solid rock that lies below the soil. Bedrock is the PARENT MATERIAL of soil.

Humus: decaying remains of plants & animals

How does soil form? Soil Living Things Help Mosses form acids that break down rock Fungi breaks down humus Earthworms, ants, prairie dogs break up soil Weathered Bedrock

Why is soil important? Supplies water and support to plants

Why is soil important? Supports human needs such as houses, buildings, roads, crops, & grazing animals.

How do soils differ? Properties of Soils Texture Size of soil particles ColorHue of soil Composition Ingredients that make up soil Permeability Movement of air & H2O through soil Porosity Space between soil particles

Soil Property #1: Texture Size of soil particles

Soil Property #2: Color Hue of a soil

Colors vary by location Red Desert Soils: CA, AZ, NV Gray Desert Soils: ID, UT, NV White Sands: NM Green Sands: Atlantic Coast Redbeds: TX, OK Yellow soil: Yellow River, China Click on pic

Minerals & Soil Colors MineralColor GoethiteYellow HematiteRed PyriteBlack (metallic) JarositePale yellow HumusBlack CalciteWhite GypsumPale brown QuartzLight gray

Soil Property #3: Composition Ingredients that make up the soil

Soil Property #4: Porosity how much space there is between soil particles H2O can be held tighter in small spaces or pores (clay) than in large spaces (sand). Think of a sieve. Smaller screens hold more water.

Soil Property #5: Permeability how easily air & water move through soil Water quickly drains through coarse, loose soils like sand. Water slowly drains through fine, firm soils like clay.

What determines the type of soil? The type of minerals & parent materials that make up the bedrock. Weathered granite forms different soil than weathered limestone. Climate Click on pic

Climate & Soil Click on pic

What affects minerals in soils? Leaching: removing or washing away of the minerals in soil On farms, these minerals need to be replaced so crops will grow. Farmers add fertilizers to replace the minerals use by plants

What is a soil profile? Soil Profile: all the layers that make up the soil in an area Horizon: soil layers

Soil Profile O Horizon: thin coating or ORGANIC material (loose leaves, decaying plants/animals) A Horizon: topsoil, a mixture of humus & rock particles. Dark in color. B Horizon: subsoil, clay, small pieces of weathered rock, & minerals C Horizon: bottom layer made of large pieces of rock that have come from weathered bedrock R = Bedrock: solid rock that lies below the soil Click on pic

Soil Uses Uses of soils depend on their properties Click on pic

Soil Uses: agriculture

Soil Uses: brick making

Soil uses: creating a pond

Forensics! Click on pic

Soil Facts 60 different kinds of soil in Lake County 400+ different kinds of soil in Ohio 70,000+ different kinds of soil in the US It takes years to make 1 inch of topsoil