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;

Earth Systems

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?

Arthur Holmes 1930’s

• Introduced supportive theory: Currents of heat and thermal expansion in the Earth's mantle move continental plates.

Convection!

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

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)

Seismology

• Seismology is the study of earthquakes.• Check out the data below that shows where

most earthquakes occur.

Volcanology

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

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)

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