Formation of the Earth

Formation of the Earth

Previous TheoriesPrevious Theories Continental Drift Theory

Developed by Alfred Wegner (1900’s)Believed continents were once all

combined into one landmass he called Pangaea meaning “All Earth”

Continents seemed to fit together like a jigsaw puzzle

Explained why fossils of the same plants and animals are found on the coast of Africa and South America

Continental Drift TheoryDeveloped by Alfred Wegner (1900’s)Believed continents were once all

combined into one landmass he called Pangaea meaning “All Earth”

Continents seemed to fit together like a jigsaw puzzle

Explained why fossils of the same plants and animals are found on the coast of Africa and South America

PangaeaPangaea

More TheoriesMore TheoriesSea Floor Spreading (1950’s)Sea Floor Spreading (1950’s)

Cracks in the ocean floor spread Cracks in the ocean floor spread apart allowing magma to rise and apart allowing magma to rise and create new ocean crustcreate new ocean crust

This helped explain underwater This helped explain underwater mountain ridges that were found mountain ridges that were found at the bottom of oceansat the bottom of oceans

Sea Floor Spreading (1950’s)Sea Floor Spreading (1950’s)Cracks in the ocean floor spread Cracks in the ocean floor spread

apart allowing magma to rise and apart allowing magma to rise and create new ocean crustcreate new ocean crust

This helped explain underwater This helped explain underwater mountain ridges that were found mountain ridges that were found at the bottom of oceansat the bottom of oceans

Mapping the World’s OceansMapping the World’s Oceans

Plate TectonicsPlate TectonicsPlate TectonicsPlate TectonicsCurrent theory of earth formation Current theory of earth formation

(1960’s)(1960’s)Lithosphere is divided in plates Lithosphere is divided in plates

that move along the magma of that move along the magma of the asthenospherethe asthenosphere

Scientists don’t know exactly Scientists don’t know exactly what causes the plates to movewhat causes the plates to move

Current theory of earth formation Current theory of earth formation (1960’s)(1960’s)Lithosphere is divided in plates Lithosphere is divided in plates

that move along the magma of that move along the magma of the asthenospherethe asthenosphere

Scientists don’t know exactly Scientists don’t know exactly what causes the plates to movewhat causes the plates to move

Possible Forces that Possible Forces that Cause Plate MovementCause Plate Movement

Possible Forces that Possible Forces that Cause Plate MovementCause Plate Movement

Ridge Push – gravity causes the oceanic lithosphere to sink into the asthenosphere

Ridge Push – gravity causes the oceanic lithosphere to sink into the asthenosphere

Ridge Push

Possible Forces that Possible Forces that Cause Plate MovementCause Plate Movement

Possible Forces that Possible Forces that Cause Plate MovementCause Plate Movement

Slab pull - because the oceanic lithosphere is denser than the asthenosphere the edge sinks and pulls the rest of the tectonic plate with it

Slab pull - because the oceanic lithosphere is denser than the asthenosphere the edge sinks and pulls the rest of the tectonic plate with it

Slab Pull

Possible Forces that Possible Forces that Cause Plate MovementCause Plate Movement

Possible Forces that Possible Forces that Cause Plate MovementCause Plate Movement

Convection – hot rock deep in the Earth rises while cooler rock sinks, which causes the oceanic lithosphere to move sideways away from the oceanic ridge

Convection – hot rock deep in the Earth rises while cooler rock sinks, which causes the oceanic lithosphere to move sideways away from the oceanic ridge

Convection