1. Changes to earth’s surface
CHAPTER 9

2. Earth’s crust Earth’s surface is constantly changing
Outer surface is a layer of rock called CRUST, it covers all the earth

3. Landforms – natural features, can be different shapes and sizes
Some form quickly, some take thousands of years

4. weathering
Weathering - the slow process of rocks in Earth’s crust being broken down into smaller pieces
Water, ice, temperature changes, chemicals, and living things ALL cause weathering
The two types of weathering
Physical weathering
Chemical weathering

5. Physical weathering Only SIZE of the rock is changed
Larger rocks are broken into smaller pieces
CAUSES
WATER - carries particle of rock, soil, and sand that scrape against the rock which causes it to become smaller
ICE - creates cracks that eventually split rocks
TEMPERATURE - when a rock is hot is expands and becomes larger, when it is cold it contracts and becomes smaller
LIVING THINGS - weeds and plants can grow in between cracks

7. Chemical weathering
Rock is broken into smaller pieces, materials that make up the rock or soil also changes
EXAMPLE
Rainwater mixing with carbon dioxide makes a new chemical that breaks down the rock
Animals, plants, and the activities of people all give off chemicals

8. Erosion
Erosion – when water, ice, gravity, and wind work together to move weathered pieces of rock

9. Deposition
pieces of rock and soil are carried by wind or flowing water
Deposition - – is the laying down of pieces of Earth’s surface
sometimes it happens slowly, other times very fast

10. As water slows, large pebbles settle first
Then, smaller sand like sink
Last, smallest called SILT AND CLAY sink too
Deposited materials forms a fan-shaped area called a DELTA

11. Wind can only carry small particles
In deserts, wind deposits grains of sand into mounds called SAND DUNES

12. Landsides No part of Earth’s surface is perfectly flat
Force of GRAVITY pulls objects from a higher place to a lower place
Sometimes they move slowly, sometimes rapidly
Landside - the rapid downhill movement of a large amount of rock and soil

13. Avalanches
In colder areas, and avalanche is the name for large amounts of snow and ice that fall rapidly down the mountain
Strong winds, earthquakes, and explosions can trigger them
Can cause a GREAT DEAL OF DAMAGE

14. Controlling erosion and deposition
Happens when the land does not have trees and other plants
People can control too!
They can grow plants
Farmers can plow fields into terraces
Along the shore, building barriers

16. volcanoes Before a volcano forms things happen deep underground
miles below ground, very hot rock, called magma, is melted into liquid
Gas in the magma forces it upward
Volcano – forms at a weak spot in the earth’s crust when magma is forced upward and reaches the surface

17. Active &dormant volcanoes
An ACTIVE volcano erupts frequently and shows signs of future eruptions
A volcano that has not erupted for a long time is DORMAT

18. Began in 1983 and has continued
Mt. Rainier, in Washington
Has not erupted in 150 years
Kileauea, in Hawaii
Began in and has continued

19. Effects of eruptions
Eruptions produce incredible amounts of rock and ash
Ash can kill trees and plant life, and wild life
Can cover nearby cities as well

20. Earth’s moving plates Earth’s outer layer is the CRUST
Below, is the UPPER MANTLE
These two layers are divided into very large pieces called PLATES
The plates move all the time
Most volcanoes are near the places where plates come together

22. Cause of earthquakes
fault - a break or crack in rock where the earth’s crust can move
Earthquake - the sudden movement that causes Earth’s crust to shake is an earthquake
Focus –- is the place underground where the plates start to move and the earthquake begins
Epicenter – the point on earth’s surface that is directly above the focus

23. Effects of earthquakes and volcanoes
Earthquakes and volcanoes can affect many places on earth’s surface
Ash can block the sunlight, making temperatures cooler
Can cause tsunamis, or huge ocean waves
Damage buildings, road, and bridges
Cause major fires