1. Processes that Change Earth’s Surface
Unit 4
Lesson 1
Processes that Change Earth’s Surface
S8.D.1.1.1,2,4

2. Weathering Breakdown of rocks into smaller pieces called sediment
3 main causes of weathering
Liquid water
Ice
Wind
examples
2 kinds of weathering
Physical Weathering
Chemical Weathering

3. Physical Weathering
rock breaks into smaller pieces but its chemical composition does not change
Also called Mechanical weathering
Unloading/ pressure release
Weathering
WIKI
Other examples

4. Chemical Weathering The chemical composition of the rock changes
Rocks break down through chemical reactions
Air and water react with minerals in rock to create various chemical reactions
Types of chemical weathering
Feldspar to Clay
Types

5. Erosion
Process by which sediment is moved over Earth’s surface by water, wind, or ice
Houses undermined by coastal erosion in Pacifica, California. Photograph courtesy of NASA.

6. Erosion Most erosion happens over long periods of time
Erosion site
Most erosion happens over long periods of time
rivers carving through land takes millions of years .
The Grand Canyon is an impressive example of stream erosion through rock
Erosion clip

7. Erosion Some erosion happens very quickly
after heavy rains, fast moving water can carry large amounts of sediment away
heavy rains can also cause landslides
Soil erosion can be prevented by planting vegetation, trees, shrubs, and other plants.
Roots of these plants will help hold soil in place. Soil will not be blown away by wind or washed away by water as easily

8. Deposition/Sedimentation
Process in which eroded sediment is dropped at another location
Deposition animation
Sediment may get transported thousands of miles by one of the world's major rivers, or it may just go from the top of the hill to the bottom during a landslide
*Increase erosion somewhere can cause an increase of sediment elsewhere

9. Deposition/Sedimentation
Most deposition happens when water or wind slow down

10. Formation of Mountains
When two of earth’s plates collide, mountains can form
The formation of mountains takes millions of years
Video clip of mountains forming
Appalachian Mountains
Pocono Mountains

11. 3 Types of Rocks
Sedimentary
Igneous
Metamorphic

12. Sedimentary Rocks Form from: Sediment Remains of living things (coal)
Sediment builds up and top layers put pressure on bottom layers squeezing the sediment together
Over time, sediment in lower layers become cemented together to form sedimentary rock

13. Sedimentary Rocks
Sandstone
Shale
Coal
Limestone

14. Igneous Rocks Magma- molten rock underground
Lava- molten rock above ground
Igneous rock forms when molten rock cools and hardens
If it cools slowly, large crystals form
If it cools quickly, small crystals form (obsidian)

15. Igneous Rocks
Granite
Pumice

16. Metamorphic Rocks
Form when heat and pressure change the chemical composition of a rock
Rocks that are buried very deep are under extreme heat and pressures
Minerals in the rock react to form new minerals
Most metamorphic rocks in Pennsylvania formed from the continental collision responsible for the formation of the Appalachian Mountains

17. Metamorphic Rocks Slate Gneiss (nice) Forms from shale
Forms from sandstone
Marble
Gneiss (nice)
Forms from limestone
Form from granite

18. Rock Cycle Rocks can cycle between types if exposed to:
heat and pressure
weathering and erosion
melting and cooling

19. Rock Cycle
Rock Cycle Animation
Rock cycle Animation

20. Fossils Evidence that organisms existed in the distant past
Can help scientists learn what ancient organisms
looked like
where they lived
when they became extinct
Can also help scientists learn about Earth’s environments in the past.
Ex. Finding a marine fossil somewhere would suggest that area was once underwater
Estimated that one in a million organisms become a fossil

21. Fossils in PA
Trilobite