Soil Evolution
description
Transcript of Soil Evolution
![Page 1: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/1.jpg)
Soil Evolution
Environmental Science
CCTI
Mrs. Conway
![Page 2: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/2.jpg)
Directions
• Read through the following slides while completing your lab packet.
• Be sure to answer all question in the packet.
• Use this button to move forward
• Use this button to move backward
![Page 3: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/3.jpg)
Where Does Soil Come From?
• Read the Background Information on your handout.
• Highlight the definitions the of new vocabulary words you encounter.
![Page 4: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/4.jpg)
What are the six components of soil?
• Rocks and rock particles
• Decaying plant and animal matter (organic)
• Dissolved minerals/ elements
• Soil air in porous spaces (aeration)
• Fungus and bacteria
• Bugs
![Page 5: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/5.jpg)
What are the two types of weathering?
• Chemical weathering can be the result of plant growth, causing a chemical change.
• Mechanical weathering occurs when water stands in the cracks of rock.
• Read through the next slides while completing page 630 in your packet.
• List and describe four types of chemical weathering and five types of mechanical weathering.
![Page 6: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/6.jpg)
Chemical Weathering
What are some examples?
![Page 7: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/7.jpg)
Chemical Weathering
Oxidation: Combines oxygen with another substance in the rock: this usually changes the color of the rock
![Page 8: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/8.jpg)
Chemical Weathering
• Carbonation: happens in rocks that contain calcium carbonate (limestone); speeds up as the temperature decreases
![Page 9: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/9.jpg)
Chemical Weathering
• Acids: formed by sulfur and nitrogen compounds and will cause rocks to fall apart
![Page 10: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/10.jpg)
Chemical Weathering
• Hydration: the incorporation of H+ and OH- ions; this addition causes an increase in volume, adding stress within the rock
![Page 11: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/11.jpg)
Mechanical Weathering
Two factors are very important for mechanical weathering, wind and water.
What are some examples?
![Page 12: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/12.jpg)
Mechanical Weathering
• Root Action: As roots grow they break rocks apart
![Page 13: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/13.jpg)
Mechanical Weathering
• Thermal expansion: especially in deserts, rocks heat up in the day and, as the temperature drops greatly at night, the rocks can flake easily (exfoliate). Freeze/thaw will deposit water in cracks when this freezes the ice pushes outward and causes pieces of the rock to break off.
![Page 14: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/14.jpg)
Mechanical Weathering
• Hydraulic Action: Water rushes into cracks in rocks; but a tiny bit of air is compressed at the crevice of the crack: when the water recedes the air is forcefully released taking away fragments of rock with it.
![Page 15: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/15.jpg)
Mechanical Weathering
• Organic Activity: Mosses and lichens attach to rocks and this causes physical as well as chemical breakdown of the rock.
![Page 16: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/16.jpg)
Mechanical Weathering
• Gravity: Large rocks often fall from mountainsides and as they hit bottom they break into smaller and smaller pieces.
![Page 17: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/17.jpg)
What is a Soil Profile?
The soil horizons make up the soil profile.
Now turn to Page 632 in your packet!
![Page 18: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/18.jpg)
Soil Profile: Click on the boxes to move forward!
O (organic)
B (Subsoil)
E (Transition Area)
C (Weathered Parent Material)
R (Parent Bedrock)
A (Topsoil)
![Page 19: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/19.jpg)
O Horizon• Colors: Black, dark brown
• Structure and Composition: Loose, crumbly, well broken up litter (twigs, leaves)
• Processes occurring: Decomposition
• Some people might not realize that this layer is actually part of the solid ground
• This layer is known as the twig-leaf layer!
![Page 20: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/20.jpg)
A Horizon
• The A horizon is made of dark colored soil called humus.
• Colors: Dark brown to yellow• Structure and Composition: Generally loose,
crumbly, well broken up because roots are present and seeds germinate here; earthworms and bugs present; minerals present
• Processes occurring: Leaching and nutrient center
• Most roots of vegetation are found here! This is the best soil for growing crops!
![Page 21: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/21.jpg)
B Horizon
• Colors: Brown, reddish to orange in color
• Structure and Composition: Zone of larger chunks, may be dense, crumbly but mostly cement-like; clay and oxidized materials and organic matter accumulates from A horizon (topsoil)
• Processes occurring: Accumulation
• This layer is less suited for growing crops!
![Page 22: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/22.jpg)
E Horizon
• Colors: Minerals are moved out from A to B (translocated) so the soil is light in color because the soil silica remains; this is also known as leaching.
• Structure and Composition: Depends upon the mass of the horizons above E; gets more compact as soil evolution develops
• Processes occurring: Transition between A and B (eluviation) where the leaching is predominant
![Page 23: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/23.jpg)
C Horizon
• Colors: depends upon the color of the parent bedrock
• Structure and Composition: Dense
• Processes occurring: Weathering or disintegration of parent material or parent bedrock
![Page 24: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/24.jpg)
R Horizon
• Colors: generally solid (gray)
• Structure and Composition: Dense
• Processes occurring: Weathering
• This layer is the parent material from which soil is made!
![Page 25: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/25.jpg)
How much did you learn?
• Complete the questions located on page 627 and 628.
• Be sure that all answers are complete.
• Use the back or forward arrows to review material.
![Page 26: Soil Evolution](https://reader035.fdocuments.in/reader035/viewer/2022062500/56814f3d550346895dbce325/html5/thumbnails/26.jpg)
You have just completed the Weathering and Soil
Formation/Evolution Tutorial!
Congratulations!