1. Teacher Information! Necessary materials: PowerPoint Guide
Presentation (ppt.)
Teacher Information!
Necessary materials:
PowerPoint Guide
**all relevant terms are bolded.
It is suggested that students read Ch. 4, pgs in Managing Our Natural Resources to be prepared for this lesson and answered discussion questions 1-6 on pg 56.
Teacher will need to teach from the notes in this PowerPoint in order for students to fill out all of the PowerPoint guide.

2. Soil Formation Pgs 46-50 in Ch.4 of Managing Our Natural Resources
Slideshow adapted from
Earl D. Lockridge
National Soil Survey Center
Lincoln, NE (
and
Pgs in Ch.4 of Managing Our Natural Resources
Soil and Water Resources

3. Students will be able to…
Presentation (ppt.)
Students will be able to…
Discuss how soil is formed.
Describe weathering processes.

4. Soil
Geologic definition: Loose surface of the earth as distinguished from solid bedrock (support of plant life not required).
Traditional definition: Material which nourishes and supports growing plants (includes rocks, water, snow, air).
Organic + Inorganic material

5. Soil
Mixture of inorganic matter (mineral), organic matter, water, and air.
Air 25%
Mineral Matter 45%
Water 25%
Organic Matter 5%

6. % Soil components varies:
Type of vegetation
Amount of mechanical compaction
Amount of soil water present.

7. Soil matters Inorganic matter
Rock slowly broken down into small particles
Organic matter
Decaying plants and animals
Decomposers are vital!
Soil formation is slow!
Soil is formed very slowly. It results from natural forces acting on the mineral and rock portions of the earth’s surface. The rock is slowly broken down to small particles resulting in soil.
New soil is continually being made, but it takes a long time to create new soil and if it isn’t managed properly, soil can be eroded away more quickly than it can be made.

8. Parent material Minerals Rocks Examples? Aggregates of minerals
Three types
Igneous
Sedimentary
Metamorphic
Parent material are the materials underneath the soil. Soil is formed from parent material.
There are five major categories of parent material (minerals & rocks, glacial deposits, loess deposits, alluvial & marine deposits, organic deposits).
Minerals are solid, inorganic, chemically uniform substance occurring naturally in the earth. What are some examples? Feldspar, mica, silica, iron oxides, and calcium carbonate
Rocks are aggregates of minerals. (An aggregate is a mass or cluster of soil particles such as a clod, crumb or granule)
Igneous rocks: lava and magma—the cooling of molten rock.
Sedimentary rocks--formed by the solidification of sediment.
Metamorphic rocks-–igneous or sedimentary rocks which have been reformed because of great heat or pressure.

9. More parent material Glacial deposits Loess deposits
Common in the Midwest U.S.
Loess deposits
Windblown silt
Eastern Mississippi Valley soils
Alluvial and marine deposits
Water-borne sediments
Organic deposits
There are five major categories of parent material.
Glacial deposits: During the ice age, glaciers moved across areas of the northern hemisphere.They ground, pushed, piled, gouged, and eventually deposited great amounts of rocks, parent material, and already formed soil material.
Alluvial deposits are left by moving fresh water.
Marine deposits are formed on ancient ocean floors.
Organic deposits are partially decayed plants that live plants are able to root and grow in.
These are found in swamps and marshes.

10. Weathering forces Rocks & minerals break down  smaller pieces
Temperature changes
Water action
Plant roots
Ice expansion
Mechanical grinding
What are examples of each weathering force?
Temperature changes—heating and cooling of rocks can cause rock to crack into smaller pieces.
Water action--Water soluble minerals dissolve when exposed to water. Some rocks may contain some minerals that are water soluble and only that part of the rock will dissolve  caves
Plant roots—Roots of plants growing in cracks in rocks can widen cracks and break rocks apart.
Ice expansion—If a rock has a crack that can fill up with water, when the water expands when it freezes. This can break rock into smaller pieces.
Mechanical grinding—wind blowing sand across rocks, or glaciers grinding rocks against each other. Example—rock tumbler

11. Organic Matter Only about 5% of most soils
Small proportion but very important
WHY is organic matter important?
Organic matter is important:
Source of plant nutrients (P, S, N)
Stores soil water---plants would not grow without these two factors.
Provides food energy for soil microogranisms
Makes soil more tillable for farming
Provides a cementing or sticky effect for the soil
--Organic matter makes life possible
Images from:

12. Organic Matter Decayed plants and animals Two types
Original tissue—still recognizable
Examples?
Humus—matter is too decomposed  unrecognizable
WHAT causes decomposition?
Examples of original tissue—twigs and leaves on forest floor
Example of humus—rich brown color in soil  decomposed material
As organisms die, they are attacked by microorganisms: fungi, bacteria, and others.

13. Review Discuss how soil is formed. Describe weathering processes.
Presentation (ppt.)
Review
Discuss how soil is formed.
Describe weathering processes.