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Tectonic Plates. Predict the layers:. Corn syrup Water Oil. Layers of Earth. picture. 2 Kinds of Crust. picture. 2 Kinds of Crust. Continental – less dense, thicker Oceanic – more dense, thinner. 2 Kinds of Mantle. Upper – solid, floats on… Lower – plastic (somewhat fluid) Why?.
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Predict the layers: • Corn syrup • Water • Oil
Layers of Earth • picture
2 Kinds of Crust • picture
2 Kinds of Crust • Continental – less dense, thicker • Oceanic – more dense, thinner
2 Kinds of Mantle • Upper – solid, floats on… • Lower – plastic (somewhat fluid) • Why?
Earth’s crust and upper mantle “float” on the plastic portion of the mantle.
Convection Currents • Movement of hot liquid or gas • Heated – rises • Cools – drops
Earth’s Crust Cracks… • Convection currents in mantle cause cracking in crust
Crustal Plates • Huge sections of earth’s crust that move relative to each other
Types of Plate Boundaries • Divergent • Convergent
Divergent Boundary • picture
Convergent Boundary • picture
Divergent Boundary • picture
Divergent O to O • New crust formed and pushed up (ridge) • Ex. Mid-Atlantic Ridge
Divergent C to C • Continent spreads, ocean basin may form • Ex. Red Sea
Convergent Boundary • picture
Ocean to Continent • Ocean plate goes below continent • Subduction • Subducted plate partially melts • Trenches, volcanic mountains • Ex. Western South America
O to O Convergent • Older slips below newer • Subducted plate melts • Volcanic islands formed • Ex. Aleutian islands, Japan
C to C Convergent • Same densities, no subduction • Compression, folding, uplifting • Ex. Himalayas, Alps
Transform faulting • Plates move past each other
Ex. – Transform Faulting San Andreas Fault
How do you think scientists identified the plate boundaries?
Ring of Fire • picture
Activity #3 – Crustal Plates • “Connect the dots” – volcanoes and earthquakes • Label 8 major plates
Pangea Theory • 1912 – Alfred Wegener • Idea that continents were once part of one large land mass – theory of continental drift
How did he know? • Continents’ shapes fit together like a puzzle • Rocks and fossils found on different continents matched
Early 1960s • Scientific evidence proves continental drift, plate tectonics, and Pangea theory