The Scoop on Soil

Of What is Soil Made?

• sand• rocks• dried plants• dead organisms• water• air

Soil Stacks Up

What are Some Processes that Form Soil?

• Decay of plant matter• Settling of volcanic ash• Transport by rain, streams, and rivers• Deposition of sediments in rivers and lakes• Weathering• Erosion

Decay of Plants

Settling of Volcanic Ash

Transport by Rain

Deposition of Sediment

Weathering

• http://video.yahoo.com/watch/1794281/5931740

There are Two Main Types of Weathering

Mechanical

Chemical

In the next 7 slides, try to determine what caused the weathering.

Erosion

• http://video.yahoo.com/watch/1794382/5933084

Erosion from Gravity

Erosion by Wind

Erosion by Water

Erosion by Ice

What’s good about erosion?• New soil is formed. Erosion results in deposits of

dark, fertile soil, perfect for growing crops.• Erosion reveals marvels of nature such as

mountains, sandstone arches, and polished cliffs.• Without erosion, rock debris would simply pile up.• Soil erosion may slow down global warming by

carrying carbon into wetlands where it is stored for long periods of time. (theory)

What’s bad about erosion?• Land can be stripped of soils needed for food to

grow.• Landslides can destroy whatever is in their paths.• Rivers can be filled with silt, disrupting their

ecosystems.• Erosion causes cracks, gaps, and ditches in the

landscape.• When soil erodes, it cannot support many types

of plant life.

What can be done to prevent erosion?

• Plant trees and bushes along riverbanks to hold soil in place.

• Plant trees that will block the wind.• Use careful, smart farming practices that

won’t disturb topsoil.• Use common-sense approaches to

construction, such as don’t build on steep slopes.

• When hiking, stay on trails.

Review

• Answer: Weathering is breaking down rock into pebbles and sand by physical or chemical processes.

1. What is weathering?

2. Give at least three examples of weathering processes.

• Answer: Wind, water, ice, heating, cooling, acid rain.

3. What is erosion?

• Answer: Erosion is the movement of Earth materials by processes such as wind, water, ice, and gravity.

4. Explain how the formation of soil is related to weathering of

rock.• Answer: Rocks are broken into small pieces by

the process of weathering. Then the small particles become part of the soil.

5. How does deposition of sediments relate to soil formation?• Answer: As sediments fall to the bottom of

rivers and lakes, they build up deposits to form soil.

6. Name at least two forces that cause erosion.

• Answer: Wind, water, gravity.

7. What is soil?

• Soil is the thin living skin that covers the land. It goes down into the ground just a short way. Soil is more than rock particles. It includes all the living things and the materials they make or change. Soil is a precious resource that sustains life on earth.

8. Name at least three layers of soil.

• Organic layer, topsoil, subsoil, rock

9. What can you personally do to help prevent erosion?

• Plant trees and bushes along riverbanks to hold soil in place.

• When hiking, stay on trails.

What process causes landslide erosion?

• gravity

CreditsThe Rock Cycle http://www.geolsoc.org.uk/rockcycleSoil Forming Factors http://soil.gsfc.nasa.gov/soilform/parmat.htmDirt: The Scoop on Soil (Amazing Science) [Paperback]Rosinsky, Natalie M (Author)The Open Door Website http://www.saburchill.com/lab/field/field02.htmlSoil Profile http://library.thinkquest.org/J003195F/newpage5.htmSoil is not dirt http://www.wsu.edu/gened/learn-modules/top_agrev/2-soil/soil1.htmlThe Dirt on Soil http://school.discoveryeducation.com/schooladventures/soil/down_dirty.htmlWhat is soil? http://www.blogdivvy.com/growing-vegetables/what-is-soil.htmGeography4Kids.com http://www.geography4kids.com/files/land_weathering.htmlTree Hugger http://www.treehugger.com/files/2008/08/greenland-crack-up.php Deadly Landslides in Guatamala http://www.guardian.co.uk/world/gallery/2010/sep/06/guatemala-landslidesWikipediaWeathering and Soils http://www.iamtonyang.com/0407/oak_leaves.jpgSoil Forming Factors http://soil.gsfc.nasa.gov/soilform/deposits.htmHow Stuff Works http://science.howstuffworks.com/dictionary/petrology-terms/volcanic-ash.htmNorth Coast Journal http://www.northcoastjournal.com/011603/cover0116.htmlJust the facts http://www.cfact.org/a/765/Ecological-benefits-of-soil-erosion