Many things cause this to happen. There are two types of weathering:

Mechanical (physical)Chemical

It is when rocks break down into smaller pieces because of some physical force. The rock does not change chemically, it just gets smaller!

Photo by A. Criminger

Freezing and thawing is breaking these rocks apart!

Photo by A. Criminger

Roots are breaking these rocks apart.

Photo by A. Criminger

Ice is breaking these rocks apart

Chemical weathering occurs when rocks are broken down by a chemical reaction. This can happen by water, oxygen, acid rain, and even living things.

Photo by A. Criminger

This rock is being broken down by the chemicals in the roots of the lichen growing on the rock.

Photo by A. Criminger

Sometimes rocks are not the only things that get chemically weathered!

Erosion now takes place.

Erosion is the moving of sediment (broken rocks and plant material) to a new location.

http://www.geography.wisc.edu/department/overview.htm

What is the evidence that sediment is being moved from one place to another?

Copyright © Marli Miller, University of Oregon

http://www.csiro.au/files/mediaRelease/mr2000/dust.htm

www.wilderness.org.au

Wind moved the sand into a dune.

A glacier is a “river” of ice that slowly moves downhill.As it travels, it breaks off rock and carries it to a new location – EROSION!

Copyright © Marli Miller, University of Oregon

Rocks moved by a glacier.

This is glacier deposition.What does the word “deposit” mean?

Copyright © Bruce Molnia, Terra Photographics

Courtesy National Oceanic and Atmospheric Administration

Glaciers form U shaped valleys.

Copyright © Larry Fellows

Copyright © Marli Miller, University of Oregon

Notice the sediment

deposited by the river and the wind.

Much of the life on earth depends on soil.

Soil is made of weathered rock and decayed parts of plants and animals.

Soil provides the nutrients needed by most plants to grow.

http://tiee.ecoed.net

Photo: A. Criminger

The first step is for bedrock to be broken down by weathering.

This weathering can happen by wind, water, or changes in temperature.

Wind Water Temperature

Copyright © Bruce Molnia, Terra Photographics Copyright © Marli Miller, University of Oregon Photo: A Criminger

Organisms such as bacteria and fungi begin to grow in the broken down bedrock.

http://waterandlife.org/MicroBiota.htm

Soil bacteria

(Image: USDA)

Soil fungi

These organisms live and die providing the soil with nutrients that other plants need to grow.

1. Rock particles2. Minerals3. Decayed plant and animal material4. Air5. Water

This is called a soil profile!

http://epod.usra.edu

North Georgia soil profile

http://www.ga.nrcs.usda.gov/technical/soils/red.html

Not all Georgia soils are red, but many of them are. The State is well known for its abundance of "Georgia Red Clay". 

People often ask why the soils are red.

The red color that is so evident in Georgia soils is due primarily to iron oxides.

Georgia soil is red because the iron in it has bonded with oxygen forming molecules of “rust.”

Without soil, life on earth would be very different.

Imagine no plants that grew in soil.No animals that grazed on plants.Where would we get our food? What would we eat? What do you think?