earth science rocks! warm up oct. 12 · it takes a long time for soil to form. soil forms as rock...

http://www.nhc.noaa.gov/

Standard: Investigate the scientific view of how the Earth’s surface is formed.

Learning Target: Today I am learning about the characteristics of soil because human survival depends on it.

How does soil form?

It takes a long time for soil to form. Soil forms as rock is broken down by weathering and mixes with other materials on the surface. Soil is constantly being formed every time bedrock is exposed. Over time, soil develops layers. We call these layers horizons.

There are 3 major horizon layers:

Horizons A, B, and C

Horizon A

• Horizon A is made up of topsoil. Topsoil is a crumbly, dark brown soil that is a mixture of humus, clay, and other minerals.

Horizon B

The B horizon is called subsoil. Subsoil consists of clay and other particles that have washed down from horizon A.

Horizon C

The first soil horizon to form from theweathering of bedrock is the C horizon. The C horizon contains only partly weathered rocks.

Below the C horizon is where you will find bedrock.

http://www.phschool.com/atschool/phsciexp/active_art/soil_layers/index.html

Page 39 IAN

1. Draw the soil profile on a pg. 39 of IAN.

2. Using page 290 in your textbook, write the descriptions of Horizons A, B and C to the right or left of your picture.

3. Complete a summary of soil horizons below your picture.