crct weathering, erosion, and soil
TRANSCRIPT
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?