1. Restless Continents
continental drift: the hypothesis by Alfred Wegener that states that the continents once formed a single landmass, broke up, and drifted to their present locations.
- many fossils & rocks
are found only on certain parts of certain continents.

2. Restless Continents
- the continents slowly drifted away from Pangaea, which was the super-continent that existed 245 million years ago. (same time as dinosaurs)

3. Restless Continents
sea-floor spreading: the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies.

4. Restless Continents
- the best evidence of sea-floor spreading comes from magnetic reversals recorded in the ocean floor.
- iron in the newly formed rock at the mid-ocean ridges has a magnetic field that is slowly spreading across the sea floor & reversing the polarity.
- this occurs once every 200,000 years

5. Restless Continents