1. Ch. 17 Sec. 1
Drifting Continents

2. Early Observers
Mapmakers were the first people to consider the idea of moving landmasses in late 1500’s
Abraham Ortelius noticed a fit of continents
Believed that continents were separated by earthquakes and floods

3. Continental Drift Theory
Proposed by Alfred Wegener
Theory proposes that all the continents were once joined together as a single landmass
Pangaea, Greek word meaning “all Earth”
Broke apart about 200 million years ago
Continents look like puzzle pieces

4. Theory Evidence Rock Formations
At separation, large land masses would have broken apart
Mountain ranges
Noticed that Appalachian Mts. & rocks in Greenland were similar

5. Theory Evidence Fossils
Similar fossils from plants and animals found on different continents
1) Land dwelling animals could not have swam a great distance
Kannemeyrid and Labyrinthodont
2) Mesosaurus, which is a fresh water reptile, could not have survived the salt water swim
3) Glossopteris, a fern in tropical weather, is found on lower continents proving that they were once closer together

6. Fossils

7. Theory Evidence Climatic Evidence Coal deposits found on Antarctica
Coal form from dead swap plants from wet and spongy areas
Glacial deposits in Africa, India, and Australia

8. Rejected Hypothesis Two Flaws First Second
Scientists did not believe that there couldn’t be enough force to move a continent
Second
Continents could not push through the ocean floor
Crustal rock way to brittle