Monday November 1, 2010

1. MondayNovember 1, 2010 • (Continental Drift and Plate Tectonics)

2. The Launch Pad Monday, 11/1/10 Why do modern birds show more of a similarity to modern reptiles than modern mammals show to modern reptiles? Birds branched off from reptiles much later than mammals did, thus retaining more of a similarity.

3. Announcements If your need to: • come in and do missing work, • remediate assessments, or • get tutoring, please sign up in the log book. We will have a test this Friday.

5. Continental DriftAn Idea Before Its Time German scientist Alfred Wegener first proposed the continental drift hypothesis in 1915. His work was published as “The Origin of Continents and Oceans.” The continental drift hypothesis states that a supercontinent called Pangaea began breaking apart about 200 million years ago. The continents “drifted” to their present positions. Continents “broke” through the ocean crust.

6. Alfred Wegener’s Pangaea Antonio Snider-Pellegrini (1858)

7. Pangaea approximately 200 million years ago Figure 7.2

8. Continental Drift Evidence Cited by Wegener • Fit of South America and Africa

9. Continental Drift Evidence Cited by Wegener • Fossils match across the seas

10. Continental Drift Evidence Cited by Wegener • Fossils match across the seas

11. Evidence Cited by Wegener • Fossils match across the seas Continental Drift

12. Continental Drift Evidence Cited by Wegener • Rock types and structures

13. Similar mountain ranges on different continents Figure 7.7

14. Continental Drift Evidence Cited by Wegener • Ancient climates – climates evidence matches on present-day continents.

15. Figure 7.A TheBreakup of Pangaea

16. Continental DriftAn Idea Before Its Time The main objection to Wegener’s proposal was the inability to find a mechanism for continental drift.

17. The Continental Drift Mechanism Discovered: Plate Tectonics The concept of plate tectonics is more encompassing than the idea of continental drift. Plate tectonics is associated with Earth’s rigid outer shell, called the lithosphere. Earth’s lithosphere consists of several “plates”, which are moving very slowly across the mobile asthenosphere below. The largest of these plates is the Pacific plate. The plates are mostly beneath the ocean.

18. Plate Tectonics The Earth’s asthenosphere lies just beneath the lithosphere. The asthenosphere is hotter and weaker than the lithosphere. This allows for the motion of the lithosphere over the asthenosphere

19. Plate Tectonics All major interactions among plates occur along their boundaries.

20. Figure 12.6

21. GEODe Earth Science Plate Tectonics Slides 698-725