1. How Does The Earth’s
Crust Move?

2. How does the Earth’s crust move?
A Discovery. . .
Geographers and cartographers in the s noticed the continents’ edges seemed to fit together like puzzle pieces.
Scientists in the 1900s mapped the edges of the continents (under the oceans) and found that the continents fit together even better.

3. How does the Earth’s crust move?
What do you think?

4. How does the Earth’s crust move?
A hypothesis is formed. . .
Scientists thought maybe the continents were once connected to each other, and have moved apart.

5. How does the Earth’s crust move?
Evidence supports the hypothesis. . .
Fossil deposits
Ancient mountain ranges
Coal deposits
Deposits from glaciers
And more. . .

6. How does the Earth’s crust move?
A theory is born. . .
Plate Tectonics
Explains how the continents move
Earth’s crust is divided into 20 sections called plates.
Plates include the crust and the top part of the mantle.
Plates float slowly on the “soupy” middle part of the mantle.

7. How does the Earth’s crust move?
Moving plates. . .
1. Heated mantle rises toward the crust.
2. As it nears the crust, the mantle cools.
Cooling chunks of mantle are pushed aside by heated mantle rising from below.
As the cooled mantle is pushed aside, it drags along the plate floating on top of it.
The cooled chunk of mantle sinks back down, and may be reheated and rise again.
The movement of the plates is called CONTINENTAL DRIFT.

8. How does the Earth’s crust move?
The plates move at about the same speed your fingernails grow!

9. How does the Earth’s crust move?
Volcanoes, earthquakes, and mountains, oh my. . .
The locations of volcanoes, earthquakes, and mountains were identified on maps.
Scientists noticed a pattern.
These locations show us where the edges of the plates can be found.
These edges are called Plate Boundaries.

10. How does the Earth’s crust move?
Earthquakes
Volcanoes
Plate Boundaries
See for yourself. . .

11. How does the Earth’s crust move?
The “Ring of Fire”. . .
Named because of the incredibly large amounts of active volcanoes.
Most of the active volcanoes on Earth are located here!

12. How does the Earth’s crust move?
Plate movement. . .
The plates move in many different directions.
Plate movement causes. . .
New crust formation
Mountains
Volcanoes
Earthquakes

13. How does the Earth’s crust move?
New crust formation. . .
Occurs when plates move away from each other
Crust is formed by hot mantle rising up and then cooling when it reaches the surface.

14. How does the Earth’s crust move?
Mountains. . .
Occur when two plates carrying continental crust collide
Whole mountain ranges form this way.
These mountains continue to grow (by centimeters).

15. How does the Earth’s crust move?
Volcanoes. . .
Occur when a plate carrying heavy ocean crust collides with a plate carrying lighter continental crust
The heavier plate moves below the lighter plate.
The heavy plate begins to melt as temperatures increase.
The melted rock moved to the surface as volcanic eruptions.

16. How does the Earth’s crust move?
Earthquakes. . .
Occur when two plates straining against each other move suddenly
Plates are connected at faults.
Earthquakes range from small and hardly felt to very large and quite damaging.

17. Any
Questions?