Evidence for Plate Tectonics

The Old Stuff and

The New Stuff

Wegener’s EvidenceThe Old Stuff

It was MY idea!

Puzzle Fit Continents

Mesosaurus Fossils

Mountain Range Evidence

Problem with Wegener’s Stuff

Oh . . . Phooey!

New Evidence for Plate Tectonics

The New Stuff

Seafloor Spreading

The seafloor contracts and sinks.

Crust spreads along an ocean ridge and magma fills the gap that is created.

Hot magma, which is less dense than the surrounding material, is forced toward the crust.

New seafloor moves away from the ridge, cools and becomes more dense than the material beneath it.

New seafloor forms as the magma hardens.

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Mantle ConvectionConvergent Divergent

Downward

Upward Arm

Slab Pull

Ridge Push

Earthquake Data

Hot Spots To get a chain of volcanoes,

the plates MUST be moving!

I knew it!

Ocean Drilling

Location Age of Rocks

Ridge Crests Youngest

Continental Margins 180 mya

Continental Crust 4.0 bya

Do you believe in Plate Tectonics?

Where are we going from here?