1. Plate Tectonics and Continental Drift TEKS Objectives: (8.3) Scientific processes. The student uses critical thinking and scientific problem solving to make informed decisions. The student is expected to: – (A) Analyze, review, and critique scientific explanations, including hypotheses and theories, as to their strengths and weaknesses using scientific evidence and information; – (E) Connect Grade 8 science concepts with the history of science and contributions of scientists. (8.14) Science concepts. The student knows that natural events and human activities can alter Earth systems. The student is expected to: – Predict land features resulting from gradual changes such as mountain building, beach erosion, land subsidence, and continental drift;

3. Earth Systems

4. Alfred Wagner 1910-1920 Introduced The Theory of Continental Drift Based theory on: – S. America & Africa – paleontology (the study of fossils) How do such large continents move?

5. Arthur Holmes 1930’s Introduced supportive theory: Currents of heat and thermal expansion in the Earth's mantle move continental plates. Convection!

6. Great Global Rift Discovered! After WW1 – Germany found a mountain-like ridge that ran through the Atlantic to the southwest of Africa. Today it is call Mid- Atlantic Ridge

7. Harry Hess 1950-1960 Introduced supportive theory: sea-floor spreading! Different plate movements gave us different land forms: – Divergent = divide (Mid-Atlantic Ridge) – Convergent = come together (Himalaya Mt. Range or Appalachian Mt. Range) – Transform = sliding (San Andres Fault)

9. Seismology Seismology is the study of earthquakes. Check out the data below that shows where most earthquakes occur.

10. Volcanology The Pacific Ring of Fire is an area of frequent earthquakes and volcanic eruptions.

11. Plate Tectonics Theory Developed from – Puzzle piecing of the continents – Paleontology (the study of fossils) – Convection (movement of heat) – Great Global Rift (aka Mid-Atlantic ridge) – Sea-Floor Spreading – Seismology (the study of earthquakes) – Volcanology (the study of volcanoes)

12. But…. What if everything I told you was old and scientists have created a new theory? This new theory is not completely accepted, but how easily do people accept change? Keep in mind that our Earth is a celestial body and star characteristics might not be to far off. http://www.newgeology.us/ http://www.youtube.com/watch?v=VjgidAICoQI&feature=related