Plate Tectonics

Early ObservationsMapmakers

Noticed the apparent fit of the continents on either side of the Atlantic Ocean

Alfred WegenerFirst proposed Continental Drift in 1912Also proposed there had been a super-continent and super-sea

Pangaea and Panthalassa• Pangaea “All The Earth” - Greek

Broke apart 200 m.y.a.Evidence to support theory

Rock FormationsFossilsAncient Climatic

Evidence From Rock FormationsFracturing of large geologic structures

Mountain ranges• Rocks from Appalachian Mountains in

U.S., England, and EuropeAge and rock types matched on separate continents

Rocks in South America and Africa

Evidence From Rock Formations

Evidence From Rock Formations

Evidence From FossilsSame fossils found on many continentsKannemeyerid and Labyrinthodont

Land-dwelling animalsCould not swim great distances between continents

MesosaurusAquatic, but fresh water

Evidence From Fossils

Ancient Climatic EvidenceCoal

Forms from dead plant on swampy landDeposits found in Antarctica• Antarctica once had a warm climate

GlaciersGlacial deposits found in Africa, India, Australia, & South America Once were located near the south pole

Ancient Climatic Evidence

Ancient Climatic Evidence

Continental Drift

Reasons Wegener’s Theory Was Not Accepted

Could not explain what caused the continents to move

What force is great enough to move the land?

Could not explain how the continents could move

Are they just plowing through the stationary ocean floor?

Exploring the Ocean FloorMajor strides in technology enabled scientists to map the ocean floor

Sonar• Used to locate submarines in WWII• Also could tell the depth of the ocean

Earthquake activityEarth’s magnetic field

Theory of Plate Tectonics 1967 Proved Wegener’s Theory

Earth’s Layers

Shield Volcanoes

Composite Volcanoes

Composite Volcanoes

Earthquakes

EarthquakesUSGS Earthquake

TsunamiSeismic Sea Wave

TsunamiUSGS EarthquakeVideoBefore and after

Andes Mountains

Himalayan Mountains

East African Rift Valley

East African Rift Valley

Transform Boundary

Transform Boundary

Plate BoundariesOceanic-Oceanic DivergentOceanic-Oceanic ConvergentOceanic-Continental ConvergentContinental -Continental ConvergentTransformMid-Continent Rifting

Oceanic-Oceanic Divergent Boundary

Oceanic-Oceanic Convergent Boundary

Oceanic-Continental Convergent Boundary

Continental-Continental Convergent Boundary

Transform Boundary

Mid-Continent Rifting

Plate BoundariesVisualizations

Transform, Divergent, and O-C ConvergentC-C Convergent

Convection Currents

Convection CurrentsVisualization

Hawaiian IslandsKauai volcanoes are inactive

No longer above hot spot

KilaueaWorlds most active volcanoSits above hot spot

Hawaiian Islands

Hawaiian IslandsMid-Plate Volcanism Visualization

Yellowstone Caldera

Plate MotionsBreakup of PangaeaFuture predictions