What’s the evidence???? Similarities of coastlines of continents (fit together like a puzzle) Discoveries and correlations of worldwide distribution of plant and animal fossils Records of Earth’s ancient magnetism captured in lava flows
What’s the evidence???? Observations of the flow of heat from Earth’s interior Studies of the nature and exploration of the ocean floor Locations of volcanoes and records of earthquakes
The evidence Wegener needed… Seafloor Spreading: The movement of the ocean floor away from either side of a mid-ocean ridge Creates NEW CRUST!!!
Mid-Ocean Ridges: A system of undersea mountain ranges that wind around the earth
Subduction: When one plate moves under another plate at a plate boundary. Why does this happen?? Oceanic crust is more dense than continental crust, so it is forced under the less dense material Zone of Subduction
Oceanic-oceanic crust Oceanic-continental crust Forms: Volcanic Island Arcs & Deep trenches
Understanding the Theory of Plate Tectonics The theory not only describes continental movement, but also proposes an explanation of WHY and HOW continents move. Tectonics is the study of the formation of features in the Earth’s crust. The theory that pieces of the Earth’s lithosphere, called plates, move about slowly on top of the asthenosphere.
CRUST: outer surface; can be oceanic or continental LITHOSPHERE: rigid interior of crust ASTHENOSPHERE: plastic upper mantle MANTLE: molten rock OUTER CORE: liquid iron nickel INNER CORE: solid iron nickel Solid rock that slowly flows (Like putty)
PLATE BOUNDARIES DivergentConvergentTransform Fault Pull away from each otherCrash into each otherSlide past each other
Normal fault Occur along divergent boundaries and the hanging wall moves downward, relative to the footwall Reverse fault Occurs along convergent boundaries and the hanging wall moves upward, relative to the footwall Strike-slip fault Occurs along transform fault boundaries and the rock on either side of fault slides horizontally Thrust fault special reverse fault where fault plane is nearly horizontal (common in steep mountains)