GEO 102 1st Edition Lecture 9 Outline of Last Lecture I What the Earth is made of Outline of Current Lecture II Original Thoughts III Dynamic Earth Today IV Evidence of Tectonics and what drives it V convection Current Lecture Original Thoughts Earth was flat stationary and young All else orbited the Earth It had always been this way It would more or less stay this way Quakes tsunamis volcanoes location of mountains continents oceans were all considered unrelated All of these thoughts were overturned The Earth is not Static Continents move Mountains form and erode away These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Mountains typically form on the active margins of the plates Oceans open and close rise and fall New Earth is formed while old is recycled It changes the deeper you go Atmosphere Oceans Continents are all dynamically linked Dynamic Earth Today The Atlantic is growing The Appalachians are shrinking eroding The Andes Himalayas Cascades and others are growing higher LA is not going to slide into the sea it will slide north to Canada South Louisiana is sinking Evidence for Tectonics is Overwhelming Magnetic reversals in sea floor rocks Paleomagnetism Common fossils and rocks on different continents Distribution of earthquakes Distribution of volcanoes Distribution of mountains Hot Spots Direct measurements of movement today What is going on New sea floor rocks are being made all the time in long ridge volcano systems Continental and oceanic rocks are different as we will learn As plates contact ocean slide beneath continents melt creating volcanoes and mountain ranges When continents strike continents both crush and form larger mountains oceanic rocks are similar dense and heavy continental rocks are heavy plate either move towards each other away from each other or move past one another What Drives it Not perfectly understood Convection of heat within the Earth Crust forms at ridges 5cm year average Plates are pulled once subducted The upper mantle and crust form a rigid lithosphere It overlies a less rigid layer called the asthenosphere The upper mantle and crust form a rigid lithosphere It overlies a less rigid layer called the asthenosphere Lithosphere where we live the crust Asthenosphere under the lithosphere under the mantle Plasticky area The movement is related to to Divergent boundaries rifts Convergent boundaries subduction Transform boundaries faults
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