Plate Tectonics- theory stating that the Earth’s crust is made up of large, moving plates

- the major force in geomorphology.

Continental Drift- Idea developed by Alfred Wegener in 1915.

- Proposed that the light continental crust “floated” on the dense oceanic crust.

- Proposed the idea of “Pangea”

- His theories were altered to create the modern view of plate tectonics.

Boundaries-Three types of boundaries:

- Convergent

- Divergent

- Transform

Convergent Boundaries-Boundary where plates push together.

- Three types:

- Continent/Continent - creates non-volcanic mountains (Himalayas)

Convergent Boundaries

Convergent Boundaries-Boundary where plates push together.

- Three types:

- Continent/Continent - creates non-volcanic mountains (Himalayas)

- Ocean/Continent - aka Subduction - creates volcanic mountains (Andes, Cascades)

- Ocean/Ocean - creates volcanic islands (Indonesia)

Divergent Boundaries-Boundary where plates pull away from each other.

- Examples:

- Mid-Atlantic Ridge (Iceland)

- Great Rift Valley in Africa

Divergent Boundaries

Transform Boundaries-Boundary where plates slide parallel to each other.

- Example: San Andreas Fault - major earthquakes

Plate Tectonics

Ring of Fire- Area of subduction around the Pacific Ocean known for volcanoes.