Continental Drift lesson

• About 200 million years ago Pangea started to break a part.

• 18o million years- Pangea is now Gondwanaland and Laurasia.

• 65 million years - Most major continentes have move apart.

• Present - the continents reach modern positions.

Broken Lands

• In the 1950’s the sea floor was mapped, was not flat and smooth

• Mid-Ocean Ridges were found

  • Underwater mountain ranges

  • Circle the earth like stitches on a baseball.

Sea floor and Pangea

• Ridges formed on cracks in the crust

• Molten rock (magma) rises through the cracks, and cools.

• New oceanic crust is made.

• Sea floor slowly spreads.

• These areas are called “Spreading Centers”

Sea Floor spreading