1. Think about the following questions and be ready to give me an answer when we begin… 1. Why does the earth look the way that it does? 2. Earth vs. people – who wins, and why?

2. Chapter 4, Section 1 Landforms (part 1)
Focus Question…
1. What physical processes inside Earth build up the land?

3. I. Forces below the Earth’s Surface
Continue to push up the surface and break it apart
Earth is composed of four layers
At the center is the Inner Core - solid metal
Outer core – mostly
liquid metal
Mantle – mostly solid
Most of earth’s mass
In this layer
Crust – thin outer layer

4. Surface is bent and broken by hot spots in upper mantle and lower crust
Magma (liquid
rock) occasionally
rises to surface
Called lava when
It breaks the
surface

5. Plate Tectonics
A theory that helps to explain how the world’s large landforms were created
Earth’s crust divided into more than a dozen ‘plates’
Yellow indicates where earthquakes occur

6. Plates move very slowly No more than a few inches a year
What would it be like if plates moved hundreds of feet per year?

7. Plates anywhere from 6 to 60 miles thick
Thinner under oceans
More dense (heavier rocks)
Thicker under continents
Less dense (lighter rocks)
Thickest parts are under mountains

8. 200 million years ago plates were together in a supercontinent called Pangaea
Pangaea broke
into smaller
supercontinents
Laurasia
(N. America
and Eurasia)
Gondwanaland
(everything else)

9. 3 types of plate movement
1. Plates moving away from each other (divergent boundary)

10. Crust moves upwards and forms a chain of mountains. Why?
Called mid-ocean ridge
Steep and jagged because they don’t erode like mountains on land
Found on every ocean floor

11. Islands occur where mid-ocean ridge rises above water
Surtsey, off the southern coast of Iceland, 16 days old (1963)

12. 2. Plates pushing against each other (convergent boundary)
A trench forms when a heavier plate dives below a lighter plate. Which plate is heavier, the ocean plate or the continental plate?
Some are 600
miles long and
60 miles wide
Up to 7 miles
deep (deepest
part of ocean)

13. If one plate is a lighter continental plate…
The lighter plate crumples and forms a mountain range
The heavier
plate sinks and
forms a trench
offshore
Andes Mtns in
S. America a
good example
Looking towards S. Pole
Andes Mtns
Trench

14. If both are lighter continental plates…
No trenches form
The Earth’s crust crumples like fenders when two cars slowly collide, forming a high mountain range
Himalayas between India and China a good example

15. What happens to rocks when the crust moves?
When rocks bend, the result is a FOLD

16. When rock layers break and move apart, the result is a fault

17. Earthquakes are caused by movement along fault lines

18. 3. Plates sliding past one another (transform fault)
Low mountains may form
The San Andreas fault in
California a good example
Lots of
earthquakes
here
Dotted line indicates fault line