Warm Up 10/14/16 11. Igneous rocks can be classified as intrusive and extrusive. Explain what that means in terms of form? 2. How are sedimentary rocks formed? How can you distinguish them? 3. What are the four agents of Erosion?

Soils

Soil 5.2 Soil  The upper layer of earth in which plants grow, a black or dark brown material typically consisting of a mixture of organic remains, clay, and rock particles. •

Soil Composition Soil is made up of four parts. These four parts are mineral matter, organic matter (humus), water, and air.

The Soil Profile 5.2 Soil Soil varies in composition, texture, structure, and color at different depths. Soil horizons are zones or layers of soil. A soil profile is a vertical section through all the soil horizons.

Soil Profile The A horizon is commonly know as topsoil The B horizon is subsoil and contains clay particles washed out from the A horizon. • The C horizon is after the B horizon and between the unaltered parent material.

A Soil Profile Showing Different Horizons

Soil Texture and Composition One way to determine a soil's composition and texture is to use a soil-texture diagram like the one shown here.

5.2 Soil  Soil Texture • refers to the proportions of different particle sizes. - Sand (large size) - Silt - Clay (small size) • Loam - a mixture of all three sizes is best suited for plant life.

Texture Triangle Used by soil scientists to define the basic textural classes Field soil scientists frequently estimate the texture by feel using their hands. For more exact measurements there are laboratory techniques that can determine the exact amount of sand, silt, and clay.

Texture Triangle Example #1 Tell me what the textural class is if we have: 42% sand, 35% silt, and 23% clay. We would have a loam!! http://www.public.iastate.edu/~arossi/texture%20triangle.jpg

Texture Triangle Example #2 What would we have if we had a soil with 8% sand, 32% clay, and 60% silt?

Texture Triangle Answer #2 http://www.public.iastate.edu/~arossi/texture%20triangle.jpg We would have a silty clay loam!!

Classwork 10/14/16 Soil Profile Handout Soil Texture Diagram (Part 1) Tutorial is in Google Classroom