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The Dynamic Earth Introduction • The Earth is an integrated system containing the geosphere, atmosphere, hydrosphere, and biosphere Geosphere • The solid part of the earth; Earth’s surface; contains rock, minerals, and sediments • Broken up into 3 categories: the crust, the mantle, and the core • However, there are layers within these 3 layers: (see next slide)… The moving Earth Destruction is surface weathering, erosion, etc. Construction is tectonics = Earthquakes, volcanoes, mountain building in general Theory of continental drift Parts of the Earth's crust slowly drift atop a liquid core. This theory is supported by fossil records. Continental Drift Theory • Wegener hypothesized that there was a gigantic supercontinent 200 million years ago, which he named Pangaea, meaning "All-earth". • Pangaea started to break up into two smaller supercontinents, called Laurasia and Gondwanaland, during the Jurassic period. By the end of the Cretaceous period, the continents were separating into land masses that look like our modern-day continents. • VIDEO Plate Tectonics Theory of plate tectonics Explains the movement of the Earth's plates and also explains the cause of earthquakes, volcanoes, mountains, etc. There appear to be 13 major plates that cover the globe. Plate Movement/ Boundaries At the boundaries of the plates, various deformations occur as the plates interact: Divergent Plate Movement: PLATES PULL APART! (Example: Seafloor Spreading) Seafloor spreading is the movement of two oceanic plates away from each other, Plate Movement/ Boundaries Convergent Plate Movement: PLATES COLLIDE! When two plates collide, some crust is destroyed in the impact and the plates become smaller. Oceanic Plate and Continental Plate - When a thin, dense oceanic plate collides with a relatively light, thick continental plate, the oceanic plate is forced under : SUBDUCTION! Two Oceanic Plates – One is pushed under the other and magma from the mantle rises, forming volcanoes in the vicinity. Two Continental Plates - Mountain ranges form! Plate Movement/ Boundaries Lateral Slipping Plate Movement: When two plates move sideways against each other, there is a tremendous amount of friction which makes the movement jerky. The plates slip, then stick as the friction and pressure build up to incredible levels: What can this cause? EARTHQUAKE! Erosion Erosion is the process that breaks down things around us, destroying and creating landforms. What causes erosion? Natural: Wind, water, etc. Human-caused: Chemicals, destruction, etc.