1. Continents change Position over Time

2. The development of Plate tectonics/ Continental Drift
Supporting detail
Main Idea
The development of Plate tectonics/ Continental Drift
CONTINENTAL DRIFT
* , Alfred Wegener proposed the theory of “ CONTINENTAL DRIFT”
*Continents had once been joined into one landmass PANGAEA (all of the continents had been joined together)

3. *Evidence for Pangea
A. Fossils -discovered fossils in eastern S. America and matching fossils in western Africa
B. Geology Land features –
mountain ranges in S. America line up with mountain ranges in Africa
rocks layers in the Appalachian mountains of N. America match rock layers in Scotland
deep scratches in rocks showed that glaciers in South Africa showed Africa was close to the S. Pole
C. Puzzle pieces – Continents fit together like a puzzle
Pangea

4. D. Alfred Wegener's idea of “Continental Drift” was NOT accepted
E. Wegener could NOT provide evidence for how the continents had moved
2. Great Global Rift is discovered
A. 1925, Germany spent two years systematically and scientifically mapped deep sea topography and the first to reveal the extent of the sea floor's rugged terrain.
B. The expedition also found that a continuous mountain-like ridge runs through the Atlantic to the southwest of Africa..
C. This ridge is now called the MID-OCEAN RIDGE

5. MID OCEAN RIDGE Use Changing Earth In your notes pages 16 and 17
Section titled “Evidence
from the Sea Floor”
In your notes
Define MID OCEAN
RIDGE with
A Circle Map
On ocean floor
MID OCEAN
RIDGE
Under water mountain
range

6. 3. Harry Hess discovers how the plates move
Seafloor spreading
Along the mid ocean ridge
Cracks open up allowing magma from the mantle to come through
The Magma cools, and hardens into rock and forms more crust
Nemo Explorer
Mantle rising through crack in sea/ocean floor allowing new rock to be made and old rock to be pushed away

7. Sea floor spreading

8. SEA- FLOOR SPREADING Use Changing Earth In your notes pages 16 and 17
Section titled “Evidence
from the Sea Floor”
In your notes
Define SEA-FLOOR
SPREADING with
A Circle Map
Molten magma from
Mantle rises and
cools
SEA- FLOOR
SPREADING
Pushes old sea
Floor away
Cools and forms
NEW ocean crust

9. Brace map shows the parts of the Theory of Plate Tectonics
1. Began with theory of Continental Drift
2. Discovery of Mid-Ocean Ridge
Theory of Plate
Tectonics
3. Discovery of the Sea- Floor Spreading process
4. Convection currents in Mantle

10. A “Flow Map" shows the Development of the THEORY OF PLATE TECTONICS
Alfred Wegener develops
Idea of Continental Drift
Harry Hess
explains
The Process
of Sea
Floor Spreading
1950
Convection
currents,
ridge push,
And
Slab pull
Abt. 1965
The Mid
Ocean Ridge
is discovered
1925
Theory of Plate Tectonics

11. Continental Drift & Theory of Plate Tectonics
Multi-flow maps show cause and effect
Causes
Effects
Mountains
Continental Drift & Theory of Plate Tectonics
Convection
Currents in the
asthenosphere
Volcanoes
Earthquakes

12. The Earth 100,000 million years from now

13. Review boundary Boundary = a border Lithospheric plates are not plates
3. Lithospheric/Tectonic Plate = a moving slab (large piece of land) that moves on the mantle in the asthenosphere
Convection currents

14. review
4 Convection currents the flow of a liquid or gas (air) from heat
Air is cooled
Cool air settles to be heated
again by candle
Hot candle heats air
Warm air rises

15. Evidence use to support Continental Drift and Plate Tectonics
1-Continental Drift Theory (all parts that Wegener proposed)
2- Evidence for activity along plate margins:
1- Earthquakes are concentrated along all three types of plate boundaries,
2- Volcanoes on the continents occur close to subduction zones.
3. Convection currents cause sea floor spreading: and the making of new oceanic crust at mid-oceanic ridges
CONTINENTAL DRIFT
1.-The good geometrical fit of the continents, (puzzle pieces).
2- Geological evidence:
similar rock types and structures were found on different continents that seem to fit
Ancient climatic evidence: Rocks formations and markings that once formed by the movement of ice sheets (glacial deposits) occur in present
3- The occurrence of identical fossils on widely separated land masses or continents.

16. Puzzle pieces Plate Tectonics Geological evidence Fossil evidence
Plate boundaries
Identifiec by earthquakes
& volcanoes
CONTINENTAL DRIFT
Plate Tectonics
Puzzle pieces
Geological
evidence
Fossil evidence
Convection currents
Cause mid-ocean ridges
& sea floor spreading