Intro

Objective 5 October 2012

Describe the theory of continental drift.

Did the Earth always look like this?

Continental Drift

Who? What? Where? When?

Alfred Wegener

Theory of Continental Drift

German scientist who developed the Theory of Continental Drift in 1912

The theory that states that the continents once formed a single landmass, broke up, and drifted to their present locations.

Restless Continents

Restless Continents

Evidence of Continental Drift

Same fossils found on opposite continents

Same rock types found on opposite continents

Warm climate plant fossils on cold climate continents

Restless Continents

Pangaea All continents were once joined as a single, giant super-continent

Greek for “all Earth”

Existed 245 MYA

Restless Continents

Restless Continents

Sea-Floor spreading

The process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies

Occurs at mid-ocean ridges (underwater mountain chains)

Restless Continents

Magnetic Reversals

Proof of Sea-floor Spreading

Magnetic North and South poles switch positions

Recorded when molten rock solidifies

Restless Continents

Summary: Alfred Wegener developed continental drift hypothesis explaining that continents once formed Pangaea and then moved to their current positions. This occurs due to sea-floor spreading and that is proved by records of magnetic reversals solidified in new ocean rock.

Objective: 5 October 2012

Outro

Describe the theory of continental drift.

If Sea-Floor Spreading continues, what will the Earth look like in another 250 MY? Describe it or draw a picture!

Restless Continents

When scientists proposed the Theory of Continental Drift, there were many skeptics. Which discovery confirmed that the continents move on plates?A. Deep-sea currents B. Earthquake formationC. Spreading of the sea floorD. Sedimentary rocks