III. Drifting Continents
A. Continental Drift—the idea proposed by Alfred Wegener that all of the continents were once joined together in a single landmass and have since drifted apart.
1. Wegener called the single landmass made of all continents Pangaea, which means all lands.
a. Over tens of millions of years, Pangaea broke apart and slowly moved to their present day positions.
2. Wegener gathered evidence from difference scientific field including land features, fossils, and evidence of climate change.
3. Wegener published his findings in 1915 in the book called The Origin of Continents and Oceans.
B. Evidence for Continental Drift
1. Evidence from land features—the mountains in parts of South America matched up with those in Africa. Coal fields in Europe matched with those in North America.
2. Evidence from fossils—Lystrosaurus and Mesosaurus both were found in areas across South America, Africa, and Antarctica. Wegener proposed that this could only be because the land was once joined.
a. Fossil—any trace of an ancient organism that has been preserved in rock.
3. Evidence from Climate—Wegener noticed that fossils from tropical plants were found in extremely cold areas such as Antarctica.
a. He proposed this was because the continents have since moved.
b. He thought Antarctica was once at a higher latitude.
c. Marks left by glaciers were found in South Africa, which is too warm today to support glaciers.
C. Wegener’s Hypothesis Rejected
1. Wegener could not provide a satisfactory explanation for the force that pushed or pulls the continents.
2. At the time, geologists thought that mountains formed because the Earth was cooling and shrinking causing the surface to wrinkle like a dried up apple.
3. Wegener pointed out for this to be correct, there should be mountains all over the planet, but there were not.
4. He thought that folding of continents pushed up huge mountains.