THE BEGINNINGS OF PLATE TECTONICS EARTH SCIENCE’S UNIFYING THEORY
WHAT IS A UNIFYING THEORY? Unifying theory: a theory that explains many natural phenomena and ties things together in an overarching way
HOW DOES IT EXPLAIN THIS?
EARTH’S STRUCTURE Crust – the thin relatively light outermost layer of the earth Mantle – thick layer of plastic rock beneath the crust Outer Core – composed of liquid iron and nickel Inner Core – solid composed of iron and nickel
OCEANIC CRUST VS. CONTINENTAL CRUST Oceanic Crust – thin, dense, composed mainly of basalt Continental crust – thick, composed of granite
BUOYANCY!
THE BEGINNINGS OF PLATE TECTONICS Alfred Wegener – a German meteorologist and polar explorer who first proposed the theory of continental drift. h?v=rDKiNwTwaNw
ALFRED WEGENER’S FINDINGS Evidence for continental drift: Continents fit together like puzzle pieces Identical fossils found on different continents Mountain ranges with identical rocks found in America and Europe BUT HE HAD NO MECHANISM.
ALFRED WEGENER SONG
SEAFLOOR SPREADING – WEGENER’S MISSING MECHANISM Seafloor spreading: The theory that new ocean crust forms at spreading centers on the ocean floor which push the continents apart.
THE AGE OF THE SEA FLOOR
HARRY HESS yMLlLxbfa4
DISTRIBUTION OF EARTHQUAKES
DISTRIBUTION OF VOLCANOES
PLATE TECTONICS
PLATE BOUNDARIES
HOW DOES IT EXPLAIN THIS?
MID OCEAN RIDGE
TRENCH
ABYSSAL PLAIN
SEAMOUNTS/VOLCANIC ISLANDS