 Aside from earthquakes, volcanoes, and landslides, Earth’s surface appears relatively unchanged on a human time scale  On geologic time scale, Earth’s surface is changing at huge rates  South America is moving away from Africa 2-3 cm/yr  Volcanic islands that make up Hawaii moving NW at 8-9 cm/yr

 First people to consider moving landmasses were early mapmakers  Explanations for continent moving included volcanoes, earthquakes, and floods  1912 Alfred Wegener proposed a hypothesis about continental movement

 Wegener’s hypothesis was called continental drift  Continental drift proposed that Earth’s continents had once been joined as a single landmass Continental drift  He called the supercontinent Pangaea, Greek word meaning “all the earth”  Proposed Pangaea began to break apart about 200 million years ago  Continents still moving slowly today

 Wegener was first person to base his idea on more than just the puzzle-like fit between continents  This was some of his evidence: (1) Evidence from rock formations (2) Evidence from fossils (3)Ancient Climate Evidence

 When Pangaea began to break apart, large geologic structures like mountain ranges would fracture as continents separated  Based on this, there should be similar rock types on opposite sides of the Atlantic Ocean  EX: rocks of Appalachian Mts share similar features with rocks in Greenland and Europe- all of these rocks are older than 200 million years old

Same rock types, structures, and ages on opposite sides of the Atlantic Ocean. –ex: Appalachians of eastern United States and Canada are just like mountain ranges in eastern Greenland, Ireland, Great Britain, and Norway. Mountain Ranges

 Similar fossils of different plants and animals that once lived on land were found on widely separated continents  Land-dwelling animals like Kannemeyerid could not have swum great distances that now exist between continents

 Used fossils from Glossopteris, a seed fern, to show that continents must have been connected and have same climate to support this plant life

 Studying sedimentary rocks, Wegener found evidence of vast climate change on past environments and climates  EX: Coal forms from dead swamp plants. Coal deposits had been found in Antarctica, supporting the idea that Antarctica must have been closer to the equator at one time

 EX: Glacial deposits (in Africa, India, Australia, and South America) nearly 300 million years old led Wegener to believe that these landmasses may have been joined and covered with ice

 Even though Wegener had lots of evidence to support his theory of Pangaea, it was rejected due to two major flaws:  (1) What was causing the continents to move?  (2) How could continents move without shattering the ocean floor?