III.Plate TectonicsPlate Tectonics A.Definition: the idea that the Earth’s crust is broken into rigid blocks called plates and these plates move. B.History: – Alexander Von HumboldtAlexander Von Humboldt Said that the coastlines of the continents show that they fit together like pieces of a puzzle. (Ex: Africa & South America) – Antonio Snider-PellegriniAntonio Snider-Pellegrini Said that all the evidence you need to agree with Von Humboldt is a map. Just look at it and you can tell that the continents fit together.

Frank Taylor (from the U.S.)Frank Taylor Said there is a crack in the Earth where new crust is being formed each day. The crack is located in the middle of the Atlantic Ocean. He called that crack the Mid-Atlantic Ridge.

Alfred Wegener (German meteorologistAlfred Wegener Developed the Theory of Continental Drift. ThisTheory of Continental Drift theory states that all the continents were once together forming a supercontinent, which he called Pangaea. His proof was that he foundPangaea. fossils on the west coast of Africa and the east coast of South America of the same plants and the same reptiles. Plant is called Glossopteris;Glossopteris; Reptile is called Lystrosauris. He also found theLystrosauris same type of rock on the two coasts.

5.1960’s – Wegener’s Theory of Continental Drift becomes widely accepted by the scientific community. WHY? Because of advances in technology. More fossils found, dated the age of rocks as the same age. Boats & submarines could look at the Mid- Atlantic Ridge. 6.Today –The Theory of Plate Tectonics states: a.Earth’s crust divided into pieces b.Pieces called plates c.Plates move a few cms each year. d.Driving force behind the plates movement is convection currents in the mantle.

e.At plate boundaries: 1)New crust is made 2)Plates slide past each other 3)Plates crash into each other 4)Subduct under 5)Plates buckle C.Plates – pieces of Earth’s crust 1.Sit on top of Mantle 2.Oceanic vs. Continental plates/crust a.Oceanic crust is very thin b.Continental crust is thick c.When two type of crust meet: Oceanic crust subducts under continental crust

3. New Crust a. Formed at Mid-Atlantic Ridge b. New crust pushes plates apart

4. Old Crust a. Destroyed at subduction zones b. Oceanic crust subducts under continental crust c. Two plates are colliding with each other 5. Boundaries a. Transform fault 1) Crack in Earth’s crust 2) Plates slide past each other 3) Ex: San Andreas Fault, New Madrid Fault

b. Divergent Zones 1) Boundaries where the plates move away from each other 2) Example: Mid-Atlantic Ridge c. Convergent Zones 1) Boundaries where plates come towards each other 2) Example: India slamming into the Eurasian Plate (makes the Himalaya Mountains taller each year by approximately 1”) 3) Subduction zone

Plate Tectonics Video