Unit 3 Continental Drift

Alfred Wegener

hypothesized that all continents were once joined together in a single land mass and have since drifted apart

Continental Drift

the idea that continents slowly move across Earth's surface

Pangaea

the name of a single land mass (a supper continent) that existed 300 million years ago

Evidence gathered to support Continental Drift Theory

land features, fossils, and climate

Landform Evidence

mountain ranges in Africa align with mountain ranges in South America

Fossil

any trace of an ancient organism that has been preserved in rock

Fossils evidence

Glassopteris (fern-like plants) fossils found in Africa, South America, Australia, India, and Antarctic. Mesosaurus and Lystrosaurus (fresh water reptiles) found in places now separated by oceans

Climate

fossils of tropical plants found on an island in Arctic Ocean, glacier deposits found in South Africa, which has a mild climate today

Wegener Theory Rejected

could not provide a satisfactory explanation for the force that pushes or pulls the continents

Rock types

rocks on opposite coasts that are the same type of rocks and the same age match up to support that they were once connected

Puzzle Pieces

the idea that the continents fit together like pieces of a puzzle.

Plate Tectonics

The theory that pieces of Earth's outer layer are in constant motion.

Convection Currents

A circular motion that occurs when a warm fluid rises cools and then sinks.

More Dense

Cooler fluids sink because they are __________ ___________.

Less Dense

Warmer fluids float because they are __________ ___________.