1. Understanding Soil Formation

2. Objectives Identify five factors involved in soil formation. Describe different types of parent material. Explain topography and how it affects soil formation. Explain how organisms affect soil development. Describe how time and weathering affect properties of soil. Explain how climate affects the development of soil.

3. Soil Formation Five factors in forming soil Parent Material Topography Organisms Time/weathering Climate

4. Parent Materials Classified by the way they were moved and scattered.

5. Parent Materials Moved by glaciers Glacial Till - No layers Can contain fine soil to pebbles to boulders Loess - occurred from blowing of soil after glaciers melted and dried Most Desirable Outwash - occurs during melting; larger items deposited first, smaller items deposited last

6. Parent Materials Deposited by flooding streams and rivers Alluvium - Bottomlands and flood planes

7. Parent Materials Bedrock - Shale, Sandstone, or Limestone Organic Matter - Usually swamp vegetation that has accumulated Known as Peat and Muck (muck is more decomposed than peat)

8. Topography Steepness(degree), length, shape, direction Nearly level soils are generally poorly drained Moderate to steep slopes are generally well drained

9. Time / Weathering Physical Weathering Temperature, Water, Wind, Freeze/Thaw Chemical Weathering Rainwater is mildly acidic Oxidation

10. Climate Rainfall - slowly by surely erodes Wind wears away at rock Hot Summer/cold Winter - Freeze/Thaw Humid area - more leaching than dry areas

11. Organisms Plants, Insects, Organisms Greatest affect on soil formation is the plants that once grew in it Native Vegetation

12. Example: common native vegetation in the Midwest. Tall Prairie Grass Prairie Soils Deciduous-hardwood forests Timber Forests How is the Midwest different from Northern Utah? Organisms