1. Dirt on Soil

2. What is Soil? Soil forms as rock is weathered and mixes with other materials on the surface. Soil forms as rock is weathered and mixes with other materials on the surface.

3. What is soil made out of? Soil composition: Soil composition: A mixture of rock particles, minerals, decayed organic material, air, and water. A mixture of rock particles, minerals, decayed organic material, air, and water. Humus is a dark-colored substance that forms as plant and animal remains decay. Humus is a dark-colored substance that forms as plant and animal remains decay. Humus is rich in nutrients that plants need to grow Humus is rich in nutrients that plants need to grow

4. Soil Particles From largest to smallest particle size: Gravel Gravel Sand Sand Silt Silt Clay Clay

5. Soil Textures Permeable means the ability for materials to let water pass through them easily. Permeable means the ability for materials to let water pass through them easily. Clay is less permeable than gravel. Clay is less permeable than gravel. If the texture is too dense (it is not permeable) and plants will not survive. If the texture is too dense (it is not permeable) and plants will not survive. If texture is not dense enough, plants may not survive either. If texture is not dense enough, plants may not survive either. Loam is made up of equal parts of clay, sand, and silt and it is the best for growing plants. Loam is made up of equal parts of clay, sand, and silt and it is the best for growing plants.

6. Horizons A soil horizon is a layer of soil that differs in color and texture from the layers above or below it. A soil horizon is a layer of soil that differs in color and texture from the layers above or below it. A Horizon (topsoil) A Horizon (topsoil) B Horizon (subsoil) B Horizon (subsoil) C Horizon C Horizon Bedrock Bedrock

7. A Horizon Topsoil: a crumbly, dark brown soil that is a mixture of humus, clay, and other minerals. Topsoil: a crumbly, dark brown soil that is a mixture of humus, clay, and other minerals. This is what you walk on outside…

8. B Horizon Subsoil: usually consists of clay and other particles washed down from the A horizon, but contains little humus. Subsoil: usually consists of clay and other particles washed down from the A horizon, but contains little humus. Below the topsoil, the subsoil is a little lighter in color color than the topsoil.

9. C Horizon Contains partly weathered rock Contains partly weathered rock This is where you will see bigger rocks and less soil.

10. Bedrock Bedrock is the solid layer of rock beneath the soil. Bedrock is the solid layer of rock beneath the soil. Once the bedrock breaks down towards the top, it continues to weather and turns into topsoil.

11. How fast is soil made? Soil develops the quickest in areas with a warm and rainy climate (temperature/climate). Areas with limestone weather quicker than areas with granite, so for rocks weathering occurs based on the type of rock and climate.

12. What else is down there? Plants contribute the most to humus, which is in the topsoil. Decomposers are the organisms that break the remains of dead organisms into smaller pieces and eat them with chemicals. Decomposers are the organisms that break the remains of dead organisms into smaller pieces and eat them with chemicals. Fungi (mushrooms and mold) Fungi (mushrooms and mold) Bacteria Bacteria Earthworms Earthworms

14. Review Questions 1. What is soil? 2. Explain how humus is helpful for soil? 3. What are the different soil horizons? 4. Put these in order from top to bottom: Subsoil Bedrock Topsoil

15. Chemical vs. Mechanical List the agents and/or processes of chemical and mechanical weathering: water, oxygen, animals, acid rain, pressure, freezing/thawing(ice), oxidation, living organisms (lichen), plant growth, abrasion, carbon dioxide, ice wedging ChemicalMechanical

16. IX. W.E.R.D.S 38- pg. 39 Weathering EQ: What is weathering? Vocabulary cut-out Matching Vocabulary cut-out Matching