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Who was the father of plate tectonics? Alfred Wegener Who was the first to propose the idea of continental drift? The theory of plate tectonics proposed that all of the continents on Earth were once a single landmass called _____________. According to the theory, this landmass broke apart how long ago? What three types of evidence supported the Pangaea hypothesis? Alfred Wegener Pangaea about 200 million years ago 1. rock formations (same rock layers were found on mountains in US and Europe) 2. fossils (similar plant/animal fossils found on widely separated continents) 3. climatic (coal found in Antarctica, so continent must have once been closer to equator) (glacier deposits found in India & South America, so continents must have once been closer to south pole True or False? Alfred Wegener died before his ideas about continental drift were recognized. What types of devices can detect small changes in the ocean floor’s magnetic field? What are ocean ridges? What are ocean trenches? True 1. Sonar 2. Magnetometers Ocean mountain ranges where earthquakes and volcanic eruptions take place long, narrow depressions in the ocean floor What is the deepest trench? Where is it located? How deep is it? Does the age of the oceanic crust increase or decrease with distance from a ridge? Is ocean sediment thickest near trenches or far from trenches? The Earth’s magnetic field is created by the movement of molten _______ in the outer core. What is it called when the Earth’s magnetic field changes direction? What causes changes in the Earth’s magnetic field? What is the study of the Earth’s magnetism? Marianas Trench/Pacific Ocean/6 miles deep What theory explains how new ocean crust is formed at ocean ridges and destroyed at deep sea trenches? This theory explains how landmasses move in _________ drifting. What theory describes how plates move and shape the Earth’s surfaces? What are tectonic plates? seafloor spreading increase near trenches iron magnetic reversal changes in iron flow paleomagnetism continental drifting plate tectonics Huge pieces of crust and upper mantle that fit together at their edges to cover the Earth’s surface How many major plates are there? 12 Name two types of boundaries 1. divergent boundaries 2. convergent boundaries divergent boundary This type of boundary is a region where plates move away from each other forming new crust This type of boundary occurs when plates move toward each other destroying crust This type of boundary occurs when plates slide past each other creating cracks What is subduction? What are the three types of convergent boundaries and what do they form? convergent boundary transform boundary When one plate moves under the other one after colliding 1. oceanic-oceanic (forms trenches, destroys basins) 2. oceanic-continental (forms trenches & volcanoes along edge of continental plate) 3. continental-continental (forms large mountain ranges) An example of this type of boundary is the Marianas Trench An example of this type of boundary is the Andes mountain range An example of this type of boundary is the Himalaya Mountains An example of this type of boundary is the San Andres Fault What cycles heat from the core to the crust? oceanic-oceanic boundary Describe how convection currents work - cooler mantle sinks (sinking current), is heated as it moves towards the core, then rises (rising current) and is cooled again divergent What type of boundaries form above rising currents in the mantle? What type of boundaries form above sinking currents? Ridge push = pushes plates _______ trenches. oceanic-continental boundary continental-continental boundary transform boundary convection currents convergent towards Slab pull = pulls plates _______ trenches down All the processes associated with the discharge of magma, hot fluids, and gases Where do most volcanoes form? volcanism True or False? Volcanic eruptions at convergent boundaries are nonexplosive. True or False? Volcanic eruptions at divergent boundaries tend to be explosive. What do you call huge piles of lava formed by nonexplosive volcanic eruptions false at plate boundaries false pillow lava Anatomy of a Volcano 1.___________= bowl-shaped area that forms around the vent 2. __________= the opening at the surface where lava leaves the pipe 3. __________= side opening of volcano where lava leaves the pipe 4. __________= tubelike structure that lava flows through to reach the surface 5. _________= large, underground pocket that holds magma; located at the base of the pipe What is a caldera? Name the types of volcanoes, what they look like, and how they are formed As the amount of gases in magma increases, the magma’s ________ increases. What is viscosity? The higher the _________ content, the greater the viscosity. Rising magma can form _______, which are intrusive rocks. What are intrusive rocks? What are extrusive rocks? 1. crater 2. vent 3. side vent 4. pipe (conduit) 5. magma chamber A caldera is formed when volcanic structure collapses into emptied magma chamber (lakes form when water collects) 1. shield volcanoes look like: gentle sloping sides, largest formed: nonexplosive eruptions 2. cinder cone volcanoes look like: steep sides, smallest formed: buildup of small magma pieces 3. composite volcanoes look like: formed: buildup of large magma chunks from explosive eruptions explosivity a material’s resistance to flow silica plutons Rocks formed from cooled magma WITHIN the crust Rocks formed when magma cools and crystallizes on the surface of the Earth