Structure of a Continent Figure 13-3. How are continental plates formed? Figure 13-4.

Structure of a Continent

Figure 13-3

How are continental plates formed?

Figure 13-4

Why was St. Louis under water during the Cambrian/Ordovician (when the fossils we saw on the field trip formed)?

What can cause the ocean level to rise, relative to the land?

Other continents were as well

What happens if the plate motions are faster?

The plates had been moving fast – the ocean seafloor was higher on average, and ocean water spilled up onto continents.

Continent-Ocean Collision

Ocean-Ocean Collision

Antilles Arc

Subduction Zone Jump

Granite plutons begin deep within an orogenic belt.

How do they get to the surface?

Granite plutons begin deep within an orogenic belt.

How do they get to the surface?

Erosion and Isostatic Rebound!

Tectonic history of North America: Growth of the Appalachians

Geometry of the Pacific – North America plates

Western Terranes

Western Terranes: The Rockies

But subduction is much more shallow than this picture shows!

Where does heating come from?

Western Terranes: Basin and Range

Canadian Rockies

Appalachians

Alps

Volcanism adds rock to continental volume.

Hotspot volcanism often begins with a large basaltic flood.

Columbia flood basalts

Columbia flood basalts: Beginning of Yellowstone hotspot

Figure 13.23A

Figure 13.23B

Iguazu River Falls (Argentina)

Iguazu River Falls (Argentina)

Iguazu River Falls (Argentina)

Iguazu River Falls (Argentina)

Shape of Atlantic Ocean determined by Iceland hotspot

Afar hotspot