1. Plate Tectonics
Chapter 4
Lesson 1
Pages

2. What are Earth’s layers?
Scientists have gathered evidence from earthquakes and volcanoes to form a model of Earth’s interior.
Earth is made of layers
Core- Earth’s central part
The inner core is made of solid metals
The outer core is made of liquid metals

3. What are Earth’s layers
MANTLE- the thick layer of solid and molten rock that surrounds the core
Top of upper mantle is solid rock
Lower mantle is solid rock
CRUST- a thin layer of solid rock that makes up the outermost layer of Earth
Imagine it as the skin of an apple.

4. What are Earth’s layers?

5. Lithosphere
The crust and the top of the upper mantle make up the lithosphere
The lithosphere is the solid, rocky crust covering the entire planet which includes landforms

6. Hydrosphere The hydrosphere covers about 70 percent of Earth’s surface
All Earth’s liquids and solid water-including oceans, lakes, and rivers, glaciers, and the water underground-makes up the hydrosphere
The hydrosphere covers about 70 percent of Earth’s surface
Most of Earth is salt water, a small fraction of Earth’s water is fresh and most fresh water is frozen (ice around North and South Pole)

7. Landforms
Physical feature on Earth’s surface. You will find these located on the crust of Earth
Mountains, hills, rivers, lakes, deserts are all examples of landforms

8. Are the continents moving?
Alfred Wegener, a geologist, noticed that the continents appeared to fit together like pieces of a jigsaw puzzle
A geologist is a scientist who examines rocks to find out more about Earth’s history and structure
He believed that millions of years ago, the continents formed 1 huge landmass known as Pangea.
The Theory of Continental Drift is responsible for Pangea breaking apart into the 7 continents
Evidence: Wegener found evidence that the mountains of the East Coast of South America had the same type of rocks as the mountains of the West coast of Africa
A Mesoraurus has been found in very old rocks in South America and Africa. It could not have been possible that this animal swam across the ocean to get from one continent to another.

9. Mesosaurus Fossil

10. What causes the continents to move?
Earth’s continent moves with these plates (see picture on page 172)
The lithosphere is described as being made of huge plates and solid rock and the asthenosphere acts as a conveyor belt that moves the plates
Magma is being pushed from the mantle toward the surface (pg. 173) and causes the land to move.
At the same time, plates are also colliding and one plate will sink under another
The ocean floor between South America and Africa is spreading at a rate of about 4cm every year and has been for the past 130 million years
Scientists developd a theory called Plate Tectonics
Earth can cause seafloors to spread and continents to move
This theory describes the lithosphere as being made of huge plates of solid rock

11. How do Mountains form?

12. How do mountains form?
When plates collide, the force that results is called compression.
This is the squeezing or pushing together of the crust
When a continental plate is compressed, the ground is forced upward and creates folded mountains

13. How do mountains form?
As the seafloor spreads, a mid-ocean ridge forms
When this occurs on land, tension pulls the crust apart and form faults
Faults are deep cracks in Earth’s crust where rocks move in opposite directions
Fault block mountains are formed as a result of this tension