Warm-up Why are there earthquakes and volcanoes ? What do you think causes it?

Alfred Wegners Theory Came up with the the Theory Continental Drift and said that there are several pieces of evidence that support it.

The Theory of Continental drift All continents were once connected as one large landmass called Pangaea. Landmass broke apart and drifted to their present positions.

Pangea Pangea was the ancient Supercontinent that existed when all of the continents were connected. If you look at a map of the continents they seem to fit together like a jig saw puzzle

Puzzle like Fit

Animal Fossils Fossils of a freshwater reptile, Mesosaurus, were found on South America and Africa. Mesosaurus could not have swam over the Atlantic Ocean.

Plant Fossils Fossils of the plant, Glossopteris, were found in Africa, India, South America, and Antarctica which all have different climates.

Glacial Deposits Eroded rocks and debris left behind by ancient glaciers can be found in South America, Africa, India, and Australia which all have different climates and are not near the poles.

Similar Rock Structures Rock formations identical to the American Appalachian Mountains can be found in Greenland and Western Europe

The Theory of Seafloor Spreading 1.On the ocean floor there are areas where the seafloor is getting bigger. 2.Researchers used sound waves to discover a system of underwater ridges or mountains that can be found all over the world.

Mid Atlantic Ridge This underwater chain of mountains and volcanoes is found in the middle of the Atlantic Ocean. dfJtNl0http:// dfJtNl0 mvX6mchttp:// mvX6mc

Why does the Seafloor Spread? 1.Hot, Less dense material below Earth’s crust rises upward to the surfaces at the mid ocean ridges. 2.Then, it, flows sideways, carrying the seafloor away from the ridge. 3.As the seafloor spreads apart, magma moves up and flows from the cracks, cools, and forms new seafloor.

Evidence for Seafloor Spreading Youngest rocks are located at mid-ocean ridges.

Evidence for Seafloor Spreading 1.Reversal of Earth’s magnetic field are recorded by rocks in strips parallel to ridges. 2.These iron rich rocks point towards magnetic North wherever it is at the time they cool.

Discussion Question How could seafloor spreading be related to continental drift?

Answer If the Seafloor is constantly spreading apart and moving, it will effect and move the continents as well.

Alfred Wegner RAFT Role: Alfred Wegener Audience: The scientific community of 1912 Form: persuasive essay Topic: Introducing the Continental drift theory Your objective is to write a first person narrative where you are Alfred Wegener who is trying to persuade the scientific community of 1912 that his theory of Continental drift is true.