PLATE TECTONICS

Description   INSTRUCTIONS: Copy the questions below. Save your answers to the questions as a single document, with each answer labeled and in the correct order. As always, proofread and run spell-check (otherwise, points off for sloppiness). When you are finished, click the Final Exam link on the Assignments page, and submit your exam either as a document upload or copy-paste, just like you have done for prior writing assignments. 1. PLATE TECTONICS (10 points) Imagine that you have taken a time-machine back to the early 1900s and are meeting Alfred Wegener for lunch. He is very depressed because almost no one believes his theory of continental drift. Explain to him how science in the decades after his death will confirm his theory and expand it into the larger theory of plate tectonics. In your explanation to him, be sure to explain: – Key discoveries about the ocean floor that happened since his day. (Note: in Wegener’s day, almost nothing was known about the ocean floor. Think about how that later changed, and how it relates to continental drift.) – Evidence that proves that the sea floor spreads and that the earth’s surface is divided up into moving plates. (Hint: this evidence includes paleomagnetism, the age of the sea floor, heat flow, and earthquakes.) 2. THE ORIGIN and PROPERTIES of WATER (10 points) – What processes do scientists think occurred early in the Earth’s history that produced the Earth’s water, including the oceans? – Water (H20) is a polar molecule. What does this mean, and what effects does water’s polarity have on its properties? – What is salinity, and what processes control ocean water’s salinity (that is, cause salinity to go up or down)? 3. OCEAN CIRCULATION (10 points) The circulation of the oceans is driven by two main processes: 1) the prevailing surface winds, and 2) differences in density between various water masses. The Coriolis effect also influences the movement of ocean currents. Use these concepts to explain: – the movements of SURFACE currents, particularly the subtropical gyres. – the movements of DEEP (thermohaline) ocean currents and the concept of “conveyor-belt circulation.” 4. COASTLINES & SOCIETY (10 points) Evaluate the effects of waves on the movement of beach sand and the resulting size of the beach. Include in your discussion: 1) an explanation of seasonal changes in the size of the beach; 2) an explanation of longshore drift; and 3) two examples of how human activities can affect the size of the beach. 5. PRIMARY PRODUCTIVITY (10 points) Why is primary productivity high in some ocean areas and low in others? In your answer: – identify areas of the ocean have generally high productivity versus generally low productivity – evaluate the reasons for those differences in productivity based on factors such as the strength of the thermocline, seasonal changes in sunlight levels, and presence of upwelling or downwelling. 6. ADAPTATIONS OF MARINE LIFE (10 points) One theme runs consistently through Chapters 14 and 15, the two chapters that discuss the major types of pelagic and benthic animals. That theme is “adaptation.” Write an essay on the general theme of how marine animals are adapted to their environment, using at least three specific examples. In other words, from the many examples described in these two chapters, pick three key adaptations (physical features and/or behavioral strategies) of marine animals that, to you, illustrate particularly well this theme of adaptation. Spread your examples around; don’t limit your examples to fish or cetaceans, but include at least one example from the benthic invertebrate animals.