1. Our Earth

2.  What do you think the earth looked like long ago?

3.  Do you think the map looked exactly the same?

4.  Could the continents have been closer together?

5.  Alfred Wegener  A scientist who believed the continents used to be close together.  He studied the world map and noticed that the continents could fit together like puzzle pieces.

6.  Theory of Continental Drift  Wegener’s belief that the continents move.

7.  Pangaea  1 supercontinent  All the landmasses combined  About 250 million years ago

8.  What was the evidence for Pangaea?  Geologic  Fossils  Glacial

9.  Geological  Similar rocks and mountains found on the coast of Southwest Africa and Eastern South America.

10.   Fossils are the remains from once living things.  The same fossils were found on the coasts of continents that fit together. Fossils

11.  Glacial  Glacial deposits (sediments) are found on continents that could have fit together.

12.  Critics  Many scientists did not believe Wegener because he couldn’t explain what force moved continents.

13.   Between the 1950s-1960s, the Theory of Plate Tectonics was developed. This theory stated that continents are part of moving tectonic plates. Evidence of seafloor spreading helped prove this. Theory of Plate Tectonics

14.  Tectonic Plates  Pieces of earth’s crust  Found on the lithosphere.  2 types:  a.)oceanic  b.)continental

15.  Seafloor Spreading  The widening of the ocean.  New oceanic crust is formed through volcanic activity.

16.  Pangaea Song