1. Weathering Erosion & Deposition

2. How does weathering and erosion affect the Earths surface?
Essential Question?
How does weathering and erosion affect the Earths surface?
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3. How does the interaction of air, water and earth shape the surface?
Essential Question PA?
How does the interaction of air, water and earth shape the surface?
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4. Student Objective:
Today I will develop an understanding of how weathering shapes the Earth’s surface.
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5. Weathering The break down of rocks and minerals due to wind, water, ice, chemical reaction, or biological matter such as plants and animals.
Water – Waves crashing into the shore
Wind – breaks off sediments leaving a
plateau of land called a Mesa
Water – When mixed with CO2 or other acids can dissolve rock and create sinkholes
Mesas- means
Explain potholes
Ice or Plant Roots –
When either get into a crack they expand or grow, breaking the rock and making the crack larger.
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6. Types of Mechanical weathering
Physical Weathering
Process by which rocks are broken down into smaller pieces by physical forces.
Types of Mechanical weathering
Ice wedging
Plant roots
Abrasion
Burrowing of animals (animal action)
Temperature changes (freezing and thawing)
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7. Plants and Animals PLANT ROOTS CAN SPLIT ROCK
Also known as: “Root pry” or “Root action”
ANIMALS DIG HOLES AND BURROW, BREAK UP ROCK

8. Ice Wedging
PROCESS IN WHICH WATER FREEZES IN THE CRACKS OF ROCK AND WEDGES (PUSHES) IT APART BECAUSE WATER EXPANDS WHEN IT FREEZES.
OCCURS WHERE THERE ARE FREQUENT FREEZES AND THAWS
July 22, 2012
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9. Abrasion The wearing away of rock material by grinding action
Usually caused by sediment in Wind and Water
Notice the rounded river rocks
July 22, 2012
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10. How decomposers enrich soil and make it fertile: mechanical weathering.
Chipmunks live in dens in the soil and search the litter for seeds and nuts.
Plant roots break up the soil and hold it in place.
Earthworms break up the soil, making it easier for plant roots to spread and for air and water to enter the soil. They create waste which makes soil more fertile by adding nitrogen.
Tell what each layer is
Horizon )- mostly decaying leaves, twigs, and animal remains and wastes
Horizon A (topsoil) Loose soil that is rich in 8 organic materials needed by plants, such as humus(comes from decaying animals and plants) and nitrogen compounds
Horizon B (subsoil) rich in minerals, such as iron and aluminum compounds, that were washed down form Horizon A by rainwater; also has hums and clays (the tiniest soil particles).
Horizon C mostly pieces of weathered rock.
Bacteria are decomposers that break down animal and plant remains and wastes.

11. Chemical Weathering
The breakdown and decomposition of rock that occurs when minerals are changed into different substances
(change in composition)
The agents of chemical weathering:
water- water dissolves rock over time
oxygen- combines with iron to form rust (oxidation)
carbon dioxide- dissolves in water to form carbonic acid
living organisms- plant roots secrete acids
acid rain- from the burning of fossil fuels
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12. Talk about how acid rain leaches aluminum from the soil and how it can end up in a body of water this can cause the youngest of the species to die Fun fact when fish die they release oxygen into the water, once the water is too oxygen rich the animals either migrate or die, this causes a deadzone in that area. Relate it back to Ecology.
Acid rain (carbonic acid) weathering the details of statues and tombstones Ex: Marble and Limestone

13. Climate Rate of Weathering
(long term pattern of moisture and temperature)
Weathering rates are faster in warm, wet climates
Desert vs. Rainforest

14. Question?????
Compare and contrast the role of air, water, and plants in chemical versus physical weathering.
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15. Why does the Earth look the way it does?
Essential Question????
Why does the Earth look the way it does?
How can maps and models be used to understand interactions on earth?
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16. Student Objective:
I will develop an understanding of how erosion and deposition shape the Earth’s surface.
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17. Erosion The movement of sediments by wind, water, ice, or gravity.
Glaciers – Push sediments down mountains carving through the land
Rivers – Carry sediments away carving out canyons
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18. Erosion by Rivers
Through erosion a river creates valleys, waterfalls, flood plains, and meanders (loop like bend in a river)
Grand Canyon Formation

19. Velocity - How fast the water moves
Streams and Rivers
Velocity - How fast the water moves
Gradient - The steepness, the slope that a river or stream travels
Discharge - The amount of water that moves past a certain point in a river in a given amount of time
If there is a steep gradient, high velocity, and a large discharge, then Erosion will be severe!
Rivers have energy to move lots of sediment, and even large boulders.

20. The more bends in the river the older it is.

21. Gravity’s Effect on Earth’s Surface
Gravity is the force that moves rock and other materials downhill.
Mass movement of rocks or sediments can be fast or slow.
The different type of mass movements caused by gravity include landslides, mudslides, slump, and creep.
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22. Erosion-Mass Movement: A large mass of sediment drops down!

23. Erosion by Gravity
Creep is the gradual movement of soil down a slope in response to gravity. This eventually results in a mass downward movement of soil on the slope.
Evidence of soil creep includes the formation of step-like ridges along the hillside, leaning walls and telegraph poles, and trees that grow in a curve to counteract progressive leaning.

24. Question???
Streams that are located on a steep slope move faster due to gravity. What effect does this have on the amount of rock or soil that these streams can erode?
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25. Deposition Sediments carried by wind, water, or ice are dropped (deposited) in a new location.
Water – Deposits sand along the shoreline to form barrier islands.
Water – Rivers carry sediments downstream and deposit them at the mouth where new land forms.
Wind – Blows sand and it builds up in hills called sand dunes
July 22, 2012
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26. Deposition
This can happen in a river when the water slows and creates a new bank, or delta.
The Mekong Delta ( “Nine Dragon river delta”) is the region in southwestern Vietnam where the Mekong River approaches and empties into the sea through a network of distributaries.

27. Question????
What are some ways in which plants, small animals, or insects might be affected by moving ice or landslides?
July 22, 2012
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28. Geologic Time Scale
Scientists use the Law of Superposition to determine the relative ages of sedimentary rock layers.
According to the Law of Superposition, in horizontal sedimentary rock layers the oldest layer is at the bottom. Each higher layer is younger than the layers below.

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30. Question????
Why is it important for scientist to study past geological process that have shaped the Earth’s surface?
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