Drifting Continents: Wegener's Hypothesis and Evidence

1. Plate Tectonics Table of Contents Drifting Continents Ms. De Los Rios 7th Grade

2. Vocabulary 5.1 • Continental Drift- the hypothesis that the continents slowly move across Earth’s surface. • Pangaea- The name of the single landmass that began to break apart 200 million years ago and gave rise to today’s continents. • Fossil- Preserved remains or traces of an organism that lived in the past. • Pangaea means “all lands” in Greek.

3. Alfred Wegener (November 1, 1880 – November 1930) • Early life and education • On November 1, 1880, Alfred Wegener was born in Berlin as the youngest of five children in a clergyman's family. • He graduated as the best in his class. Afterward he studied Physics, meteorology and Astronomy in Berlin. • He was a German polar researcher, geophysicist and meteorologist. • During his lifetime he was primarily known for his achievements in meteorology and as a pioneer of polar research, but today he is most remembered for advancing the theory of continental drift (Kontinentalverschiebung) in 1912, which hypothesized that the continents were slowly drifting around the Earth. • His hypothesis was controversial and not widely accepted until the 1950s, when numerous discoveries such as palaeomagnetism (the study of the record of the Earth's magnetic field in rocks) provided strong support for continental drift, and thereby a substantial basis for today's model of Plate tectonics.

4. What Was Wegener’s Hypothesis About the Continents? • In 1910, a German scientist named Alfred Wegener became curious about why some continents look as though they could fit together. • Wegener’s hypothesis was: • that all the continents were once joined • together in a single landmass and have • since drifted apart. • Wegener’s idea that the continents moved • over Earth’s surface became known as • continental drift.

5. What Was Wegener’s Hypothesis About the Continents? • According to Wegener: • The continents were joined together in a supercontinent, or single landmass about 300 million years ago. • Wegener called the supercontinent Pangaea. • Over tens of millions of years, Pangaea began to break apart. • The pieces of Pangaea slowly moved toward their present-day locations. • These pieces became the continents as formed today.

6. Wegener’s Book • In 1951, Wegener published his evidence for continental drift in a book called The Origin of Continents and Oceans.

7. Piecing It All Together The coastlines of some continents seem to fit together like a jigsaw puzzle. 1. Draw an arrow to match the numbered coast with the lettered coast that seems to fit. 2. How would a continent’s climate change if it drifted closer to the equator? ________________________________________________________________________________________________________________________________________________ Drifting Continents pg. 173 Fig. 1

8. Wegener’s 3 Pieces of Evidence • Land features • Fossils • Climate change

9. Evidence #1 From Land Features pg. 173 • Land features on the continents such as mountain ranges and coal fields provided Wegener with evidence for his hypothesis. • He pieced together maps of Africa and South America. • He noticed how the coal fields lined up. • He also noticed that coal fields in Europe and North America also match up.

10. Evidence From Fossils pg. 174 • Wegener also used fossils to support his hypothesis for continental drift. • A fossil is any trace of an ancient organism that has been preserved in rock. • Plant fossils such as Glossopteris (fernlike plant) found in various continents Africa, South America, Australia, India, and • Antarctica. • Freshwater reptiles such as Mesosaurus and Lystrosaurus found in places that are now separated by oceans (reptiles that could not swim long distances)

11. Drifting Continents Fig. 2 Pg. 174 Pangaea and Continental Drift Many types of evidence suggest that Earth’s landmasses were once joined together.

12. Glossopteris Mesosaurus

13. Evidence #3 From Climate pg. 175 • Wegener also used evidence of climate change to support his hypothesis. • As continents move towards the equator= climates warmer as they move towards the Poles= Colder. • As continents moves, they carry along fossils and rocks formed at all its previous locations. • Wegener’s Hypothesis Rejected • Wegener could not provide a satisfactory explanation for the force that pushes or pulls the continents. Because he could not identify the cause of continental drift, most geologists of his time rejected his idea. • Apply it! & Assess your Understanding

14. RESOURCES • Online activity • Rock Activity BBC • Brainpop Plate Tectonics