Transcript Earth`s Plates in Motion - Etiwanda E

From Pangea to Plate Tectonics
Earth’s Plates In Motion
Andrew Flint
August 8, 2002
Contents
•
•
•
•
•
What is Pangea?
The theory of Continental Drift
Seafloor Spreading
What is Plate Tectonics?
Timeline
• Questions
• Ideas for further study
• Bibliography
Pangaea
• The word “Pangaea” means “all land”
• Scientists believe that the continents once
looked like this:
Alfred Wegner and the Theory
of Continental Drift
• In 1912 Alfred Wegner theorized that the
continents had once been together and had
“drifted apart. They fit together like puzzle
pieces.
• Rock formations, climate similarities, and plant
& animal species gave further evidence.
Seafloor Spreading
• In the 1950’s scientists began to look at the
ocean floor for evidence of this movement.
• They noticed deep sea trenches and rifts.
• Age Evidence and Magnetic Clues provided
further evidence that Wegner had been correct!
Plate Tectonics
• In the 1960’s scientists theorized Plate Tectonics.
• Earth is made of 10 plates that “slide” around on
the plastic-like layer of the earth below the crust
called the asthenosphere.
Plate Boundaries
• Convergent- Plates collide…volcanoes,
mountains
• Divergent- Plates move apart…ridges, rift
valleys
• Transform- Plates slide past one
another…earthquakes
Timeline
• 1912 Alfred Wegner-Continental Drift
• 1950’s Seafloor Spreading
• 1960’s to present- Plate Tectonics
Do You Remember?
• 1. Define Pangaea.
• 2. Describe Wagner’s theory.
• 3. What evidence is there of Seafloor Spreading?
• 4. Describe Plate Tectonics.
• 5. Name and describe the 3 Plate Boundaries.
I’d Like To Know More…
• How much do the plates move in a year?
• Which direction are we moving in?
• Can we stop the movement?
(earthquakes)
Bibliography
• Earth Science, Glencoe/ McGraw Hill.
Columbus, Ohio, 2001
• Research and images ,
http://www.enchantedlearning.com