What happens at Divergent Boundaries? Divergent boundary forms on a continent it is called a rift or continental rift. Example: African Rift Valley, Iceland

What happens at Divergent Boundaries? Divergent boundaries that form under the ocean is called an ocean ridge. Example: Mid-Altantic Ridge

Age of Oceanic Crust

What happens at Convergent Boundaries? Tectonic plates move toward each other or collide. Three types of convergent plate boundaries: Continent-continent Continent-Oceanic Oceanic- Oceanic

What happens at Convergent Boundaries? Continent-Continent Convergent Two continental plates collide forming a mountain. Example: Indian plate collided with Eurasian plate created the Himalayan Mountains

What happens at Convergent Boundaries? Continent-Oceanic Convergent Also called subduction Dense ocean crust sinks beneath the continental crust forming a trench.

What happens at Convergent Boundaries? Oceanic-Oceanic Convergent Denser oceanic plate sinks below the other (also called subduction) Creates oceanic volcanoes

What happens at Transform boundaries? Edges of tectonic plates are sliding past one another. Example: San Andreas Fault in California

History of Continental Drift Abraham Ortelius -1500’s : thought that North & South America were separated from Europe and Africa by floods and earthquakes. Eduard Suess—1800’s: believed Southern continents were once joined together as a single landmass, called Gondwanaland Alfred Wegener—1912:proposed the theory of continental drift, but it was rejected by the scientific community

Gondwanaland

Wegener’s theory & Pangaea Earth’s continents were once joined as a single landmass. Called it Pangaea, which means “all the Earth”. It broke apart 200 million years ago Continents have been drifting to their current positions.

Pangaea

Evidence for Continental Drift 1. FIT OF THE COASTLINES the coasts of South America and Africa fit together like a puzzle in the Atlantic Ocean

Evidence for Continental Drift 2. SIMILAR ROCK FORMATIONS Rocks in areas that were once joined have the same age and structure, such as the Appalachian Mountains and mountains in Greenland and Europe.

Evidence for Continental Drift 3. FOSSILS Fossils of land animals and plants were found in widely separated continents. These fossils are all the same age, which suggests that all land was once joined. Glossopteris (an ancient fern-like plant) Mesosaurus (a small aquatic reptile)