Chapter 7

  1. Who is credited with developing the continental drift hypothesis?- Alfred Wegener

  2. What was probably the first evidence that led some to suspect the continents were once connected?-

  3. What was Pangaea?- A supercontinent made up of all of our current continents

  4. List the evidence that Wegener and his supporters gathered to substantiate the continental drift hypothesis.- The fit of South America to Africa, the geographic distribution of fossils, rock structures, and ancient climates

  5. Explain why the discovery of the fossil remains of Mesosaurus in both South America and Africa, but nowhere else, supports the continental drift hypothesis.- These two continents were connected which would give the creature the ability to populate the area. Additionally, when Pangea broke apart, it did so in stages with South America and Africa being connected the longest

  6. Early in this century, what was the prevailing view of how land animals migrated across vast expanses of ocean?- Scientists believed taht land animals migrated using transoceanic bridges (isthmian links)

  7. How did Wegener account for the existence of glaciers in the southern landmasses, while at the same time areas in North America, Europe, and Siberia supported lush tropical swamps?- The configuration of Pangea meant that the southern continents were located close enough to the South Pole to have the conditions necessary to generate extensive expanses of glacial ice

  8. On what basis were plate boundaries first established?- The locations of earthquakes

  9. What are the three major types of plate boundaries? Describe the relative plate motion at each of these boundaries.- Divergent boundaries (two plates move apart), Convergent boundaries (two plates move togetehr), Transform fault boundaries (two plates grind past each other)

  10. What is seafloor spreading? Where is active seafloor spreading occurring today?- Seafloor spreading is the mechanism that operates along the oceanic ridge system to create new seafloor; Mid-Atlantic Ridge and East Pacific Rise

  1. What is a subduction zone? With what type of plate boundary is it associated?- Convergent boundaries; Convergent boundaries

  1. Where is lithosphere being consumed? Why must the production and destruction of lithosphere be going on at approximately the same rate?-

  1. Briefly describe how the Himalaya Mountains formed.- the subcontinent of India “rammed” into Asia, the continental crust buckled and fractured and was generally shortened and thickened

  2. Differentiate between transform faults and the other two types of plate boundaries.- Transform fault are different from other plate boundaries because there is no production or destruction of the lithosphere

  1. Some predict that California will sink into the ocean. Is this idea consistent with the theory of plate tectonics?- No, because plate tectonis has to do with movement on a horizontal plane and not the levels of the ocean

  1. Define the term paleomagnetism.- the Earth’s magnetism (where the magnetic poles were) in ancient times, as demonstrated by fossils from millions of years ago

  2. How does the continental drift hypothesis account for the apparent wandering of Earth's magnetic poles?- Because the magnetic poles align closely with the geographic poles, the loctaion of those poles would seemingly change with continental drift

  1. What is the age of the oldest sediments recovered by deep-ocean drilling? How do the ages of these sediments compare to the ages of the oldest continental rocks?- 180 milllion years old; Continental crust has been recorded to be as old as 4 billion years old

  1. How do hot spots and the plate tectonics theory account for the fact that the Hawaiian Islands vary in age?- The hot spots contribute to building the islands, and as they drift, more islands can be formed by the hot spot

20. Briefly describe the three mechanisms that drive plate motion.- Slab pull (the dense slabs of lithosphere sink into the aesthenosphere and “pull” the trailing plate along), Ridge push (slabs of lithosphere “slide down the flanks of the risge due to gravity), Slab suction (an induced mantle circulation that pulls both the subducting an doverriding plates toward the trench)

  1. With what type of plate boundary are the following places or features associated: 1) Himalayas, 2) Aleutian Islands, 3) Red Sea, 4) Andes Mountains, 5) San Andreas Fault, 6) Iceland, 7) Japan, 8) Mount St. Helens?- 1) Convergent 2) Convergent 3) Divergent 4) Convergent 5) Transform Fault 6) Convergent 7) Convergent 8) Convergent