Plate Tectonics Plate Tectonics 011916 What is Earth

Plate Tectonics

Plate Tectonics 01/19/16 What is Earth made • up of ? ? Earth is made up of compositional layers: crust, mantle & core. Earth is made up of physical layers: lithosphere, asthenosphere, mesosphere, outer core & inner core. – Some of these layers are solid, some are liquid. • • Geologic evidence supports plate tectonics. Alfred Wegener proposed his hypothesis of continental drift. – Continental drift states that the continents were once one landmass, that broke up and then drifted to their present locations. • Evidence for continental drift includes similar fossils, rock formations, and mountain ranges on different continents, and continent shape. • What evidence suggests that continents move? ?

Plate Tectonics What evidence suggests that continents move continued…. . 03/12/15 – Continental drift states that the continents were once one landmass, that broke up and then drifted to their present locations. • Evidence for continental drift includes similar fossils, rock formations, and mountain ranges on different continents, and continent shape. What is Pangaea ? ? • Scientists think that about 245 million years ago, the continents were joined in a single large landmass they call Pangaea. What discoveries support the idea of continental drift ? ? • Scientists began to map out the sea floor. They discovered huge under-water mountain ranges called mid-ocean ridges. . •

Plate Tectonics 03/12/15 What discoveries • support the idea of continental drift continued…. Sea-floor spreading is the process by which new oceanic lithosphere sea floor forms when magma rises to Earth’s surface at mid-ocean ridges and solidifies, as older, existing sea floor moves away from the ridge. • • Tectonic plates are in motion. The theory of plate tectonics states that Earth’s lithosphere is made of large pieces called tectonic plates that are in constant motion as a result of density differences caused by the transfer of energy as heat inside Earth. – A tectonic plate is a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle. What is theory of plate tectonics ? ?

Plate Tectonics 03/12/15 What is theory of • plate tectonics continued…. The theory of plate tectonics states that Earth’s lithosphere is made of large pieces called tectonic plates that are in constant motion as a result of density differences caused by the transfer of energy as heat inside Earth. – A tectonic plate is a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle. • Tectonic plates move around on top of the asthenosphere. – Continental crust is thicker, and less dense than oceanic crust is. What are three types of plate boundaries ? ? Tectonic plates meet at plate boundaries. Plate boundaries may be on the ocean floor, around the edges of continents, or even within continents. • •

Plate Tectonics 03/12/15 What are three types of plate boundaries continued…. . • • Tectonic plates meet at plate boundaries. Plate boundaries may be on the ocean floor, around the edges of continents, or even within continents. – Convergent boundaries form where two plates collide. – Divergent boundaries form when two plates move away from each other. – Transform boundaries form when two plates move past each other horizontally. What causes plate tectonics to move? ? • Three possible mechanisms for tectonic plate motion are mantle convection, ridge push, and slab pull. Essential Question: 1. What is plate tectonics? ? (Be sure to thoroughly explain and provide at least one example. )

The end !! Questions ? ?