Continental Drift
• Scientists used to wonder why it looked like the earth’s land masses (continents) appeared like a puzzle, and was it possible they would together?
• Look at the map of the world……what do you see?
Alfred Wegener
• He did more research on it…..what did he find out?
• Biological evidence – fossils of the same species were found in totally separate parts of the world. (see p. 383)
• Wegener’s theory – the continents had gradually moved to their present location. He called this theory…CONTINENTAL DRIFT
He found more “ROCK-solid” evidence
• Geologists had found similar rocks on both sides of the Atlantic Ocean
• Appalachian Range Britain
Trilobites – ancient sea creatures
• From bottom of the ocean to the top of the world, found in the Himalayas
• These ancient ocean dwellers are fossilized at the top of the mountain
range.
Advances in Technology
• These helped to prove Wegener’s theory • SONAR – sound wave technology helped to
map the ocean. It amazed everyone• There were mountains just like on land.• Mid-Atlantic Ridge – a mountain range from
North to South along the middle of the Atlantic ocean. (see Google Earth)
Sea Floor Spreading
• Scientists could confirm that the sea floor was spreading when they gathered samples in submersibles.
• Older rock was further away from the ridge, newer rock was close to the ridge.
New Igneous Rock
The Conclusion is???
• Theory of Plate Tectonics-The earth’s crust is made up of plates, like rafts, and they are always moving on the liquid Mantle.
How do plates move?
• Converging Plates – plates pushing together, against each other.
• Causes mountain ranges, volcanoes• Two continental plates = mountains• Continental + oceanic plate = volcanoes
• Diverging Plates – plates moving/pulling away from each other
• Causes rift valleys on land, ocean ridges