9.1 – Continental Drift

Do Now What are 4 types of evidence to support the continental drift hypothesis?

Do Now What are 4 types of evidence to support the continental drift hypothesis? The Continental Puzzle Matching Fossils Rock Types and Structures Ancient Climates

Key Word Evidence Organism Mechanism

Vocab Words Continental Drift Pangaea

Alfred Wegener 1880-1930 A German Scientist (Meteorologist) Proposed a radical hypothesis in 1915 called the continental drift hypothesis. Stated that the continents had once been joined to form a single supercontinent. Supercontinent was called Pangaea, meaning all land. He also hypothesized that about 200 million years ago Pangaea began breaking into smaller continents. He and other collected evidence to support these claims.

Evidence The Continental Puzzle Matching Fossils Rock Types and Structures Ancient Climates

The Continental Puzzle Wegner first thought that the continents might have been joined when he noticed the similarity between the coastlines on opposite sides of the South Atlantic Ocean. He used present-day shorelines to show how the continents fit together.

Matching Fossils Fossil evidence for continental drift includes several fossil organisms found on different land masses. Wegner reasoned that these organisms could not have crossed the vast oceans presently separating the continents.

Rock Types and Structures Several mountain belts that end at one coastline, only to reappear on a landmass across the ocean. We look at the rock type and structure to determine that the same mountain range can range throughout different countries that normally are separated by miles of ocean. Appalachian Mountains (North America) and Caledonian Mountains (Europe) When the continents fit together in Pangaea the mountain range is a continuous belt.

Ancient Climates Wegner found evidence of ancient glaciers with an artic climate in areas that are now tropical or subtropical.

Rejecting a Hypothesis Wegner’s drift hypothesis faced a great deal of criticism from other scientists. One thing Wegner could not describe was a mechanism that was capable of moving the continents across the globe. He had all the evidence, he just could not explain what caused the movements. Therefore, his hypothesis was rejected by many scientists during Wegner’s time.

Creating a New Theory After Wegner made the continental drift hypothesis, major strides in technology enabled scientists to map the ocean floor. Then we had a lot of new data on earthquake activity and Earth’s magnetic field. In 1968, these new findings led to a new theory, known as the Plate Tectonics Theory. Provides the framework for understanding most geologic processes.

Explain the evidence found Group Activity Fill in the chart about the types of evidence for the continental drift hypothesis.   Evidence Explain the evidence found