Name Learning Unit 2 Plate Tectonics and Physical Hazards Review Questions This assignment is designed to assess your understanding of Unit 2 and includes some of the Questions for Review at the end of Chapter 2 from your text plus a few additional questions Each question can be answered in one to two sentences Please limit yourself to a maximum of three sentences Access the assignment complete it with ANSWERS IN A DIFFERENT COLOR FONT as a separate file and send it back for evaluation and grading through the assignment tab by or before the due date 1 What forces drive internal and external Earth Processes Internal processes such as magma formation to create volcanoes and the storage of strain energy in rock to create earthquakes are driven by heat loss from Earth s deep interior External processes processes resulting from the hydrologic cycle take place near the surface or at the surface of the earth and are driven by gravity and energy from the sun 2 What energy sources caused the interior of the early Earth to heat up gravitational collapse impact energy and radioactive decay 3 List the density stratified layers of the earth from most dense to least dense Inner core outer core mantle oceanic crust continental crust 4 The lithosphere is composed of what two layers Crust oceanic and continental and upper mantle 5 Distinguish between Earth s lithosphere and asthenosphere in terms of both location and properties The crust and the upper part of the mantle is called the LITHOSPHERE and it is RIGID BRITTLE and behaves ELASTICALLY The part of the mantle directly below the lithosphere is termed the ASTHENOSPHERE which behaves like a PLASTIC a solid that flows 6 Before people understood plate tectonics what evidence led some scientists to believe in continental drift Match of coastlines across the Atlantic Ocean Match of rock formations across the Atlantic Ocean Distribution of fossil species across continents Distribution of climate sensitive sedimentary rocks 7 What was the primary reason why Alfred Wegener s theory of continental drift rejected He had no viable mechanism for moving continental crust 8 What evidence confirmed seafloor spreading Be brief but to the point Some evidence includes Reversals of the Earth s magnetic field are preserved in ocean floor basalt as matching symmetrical striped patterns parallel to the mid ocean ridge The youngest ocean floor rock is at the ridge and the oldest ocean floor rock is farthest away from the ridge Hot spot volcanic islands show the direction of motion of the lithospheric plate over the mantle plume Earthquakes and volcanoes are concentrated where plates interact at their boundaries 9 If the ocean floor is getting wider why is the Earth not becoming larger Old ocean floor sinks at subduction zones trenches 10 Why do many oceanic volcanoes occur as long lines of volcanoes that are active at only one end They are hotspot volcanoes A hot plume of magma rising through the mantle burns through the overlying lithosphere to erupt as a volcano Since the lithosphere moves over the deeper mantle new volcanoes form progressively in a line over the plume 11 What are the main types of lithospheric plate boundaries in terms of relative motions Provide a real example of each Continent Ocean Convergent Plate Boundary Examples include the Andes Mountains in South America the Cascade Mountains in Western US Continent Continent Convergent Plate Boundary Examples include the Appalachian Mountains formed during the formation of Pangaea the Himalayas from the collision of India with Asia Ocean Ocean Convergent Plate Boundary Examples include Japan Aleutian islands Caribbean islands Mariana Islands Continent Continent Divergent Boundaries Examples include The break up of Pangaea The East African Rift Valley Basin and Range of Nevada and Utah Ocean Ocean Divergent Boundaries Examples include Mid Atlantic Ridge spreading 1 cm yr East Pacific Rise spreading 6 cm yr Ocean Ocean Transform Boundaries or Ridge ridge transform boundaries Major offsets of mid ocean ridge axis Continent Continent Transform Boundaries Examples include the San Andreas Fault North Anatolian Fault 12 Why does oceanic lithosphere almost always sink beneath continental lithosphere at convergent plate boundaries Oceanic lithosphere is denser heavier than continental lithosphere 13 With which type or types of boundary are active volcanoes generally associated Divergent or spreading convergent or subduction 14 How does magma form in the line of arc volcanoes over an active subduction zone Melting of the subducting oceanic plate occurs because it is not stable under the high temperatures and pressures of the mantle therefore it melts generating a mafic magma The magma being less dense than the surrounding solid mantle rises up through the continental felsic crust The end result is a volcanic arc paralleling the oceanic trench 15 Along which type or types of lithospheric plate boundary are earthquakes common All convergent divergent and transform
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