Continental Drift Theory Alfred Wegener Early 1900’s Examined and compiled data of fossil, rock, glacier and design of earth’s continents The ‘what’ of earth change, not the why nor how

Puzzle Pieces South America and Africa North America and Europe

Rock Evidence Different continents with same age, type, design of form

Glacier and Mineral Deposits Same deposits on different continents all over the world.

Fossil Evidence Glossopteris- plant Mesosaurus- animal

Ocean Floor? Entirely unknown Too difficult to study Environment studied during WWII WHY?

Ocean Floor Revealed! Necessity is the mother of invention- author unknown Ocean floor mapping for submarine offense and defense during WWII Data compiled after war in the late 40’s and 50’s

Mid Ocean Ridges Mid Ocean Ridges made visible Mountain Ranges on all ocean floors Continuous crust of Earth includes basaltic oceanic crust

SO…. Fissures in ocean floor and other features led to new ideas New information, new ideas New data, new theories

Theory of Plate Tectonics Plates moving in 3 basic directions Motion displayed in earthquake and volcanic data EQ and Volcanic data outline plates

Plate Motions Subduction Transform Boundary Ocean floor spreading

EQ and Volcano Data Earthquake data plotted Volcano data plotted Earth shows patterns of plate boundaries not visible nor known prior to ocean floor topography or data plotted

Why do plates move? Asthenosphere Properties of asthenosphere are semi-solid Flowable material

Energy transfer Energy is transferred in 3 ways: Conduction Convection Radiation

Convection Currents in Mantle Material moves from heated, more energetic region due to heat, to cooler region, where molecules condense, become less active, more dense and sink. Cycle continues

YOUR TURN… Use resources to diagram the motions of the plates and identify at least one place on the Earth where each motion occurs.