Plate Tectonics

Chapter 17.1

Layers of the Earth

Alfred Wegener

1912 – Proposed the theory of Continental Drift

Supported by fossil and rock type evidence

“Pangaea” His theory was disregarded and

mocked by the science community

Continental Drift

Continental Drift

Convection Currents

Plate Boundaries

Plate Boundaries

Divergent Boundary – moving apart Convergent Boundary – moving

together Transform Fault Boundary – moving

sideways past each other

Divergent boundary of two continental plates.

Convergent boundary of two oceanic plates.

Convergent boundary of an oceanic plate and a continental plate.

Convergent boundary of two continental plates.

Transform-fault boundary where the North American and Pacific plates are moving past each other.

Evidence for Plate Tectonics

1960s – Geologic Survey on the Mid-Atlantic Ridge

Magnetic “bands” were observed The Bands magnetic polarities were

alternating