Continental Drift

The theory of Continental Drift is supported by

1. Geographic Fit of continents (e.g. South America & Africa)
2. Similar fossils on continents separated by oceans
3. Similar rocks on both sides of the Atlantic
4. Glacier Landforms & Striations
5. Tropical fossils in Polar areas
6. Seafloor magnetism (spreading oceanic crust)
7. Paleo-magnetism of rocks.

Plate Boundaries

Ocean/Continent

Convergent boundary - Oceanic plate subducts under the continental plate.
            Landforms - Ocean Trench, Young Mountains

 

Transforming boundary - Horizontal plate movement.
            Landforms - Faults

 

Ocean/Ocean

Convergent boundary - Subduction of one ocean plate under another.
            Landforms - Deep ocean trench, Volcanic Island Arcs

 

Divergent boundary - Occurs along the mid-oceanic ridge, where new plates are constantly being formed from upwelling magma.
            Landforms - Mid-ocean ridge, Undersea volcanoes, black smokers.

 

Transforming boundary - Faults occur along the mid-ocean ridge when different spreading rates occur.
            Landforms - Faults

 

Continent/Continent

Convergent boundary - Two continents collide and create the largest mountains
            Landforms - Mountains, No volcanoes!!

 

Divergent boundary - Continental rift valley

 

Transforming boundary - Transform Fault