Plate Tectonics Worksheet
Answer the lab questions for this week and summarize the lab experience using this form. Carefully read Ch. 8 of Geoscience Laboratory. Complete this week’s lab by filling in your responses to the questions from Geoscience Laboratory. Although you are only required to respond to the questions in this worksheet, you are encouraged to answer others from the text on your own. Questions and charts are from Geoscience Laboratory, 5th ed. (p. 133-150), by T. Freeman, 2009, New York, NY: John Wiley & Sons. Reprinted with permission.
8.4 Which has the greater proportion of Iron, Magnetite, or Hematite? Hematite
8.7 When the reverse switch of a drill is thrown the drill rotates in the opposite direction. How does that affect the drill’s circuitry? The flow of electricity produces a magnetic field and a loop of wire within a magnetic field produces a flow of electricity, when the switch is thrown it reverses the magnetic field making drill spin in the direction of the current flow. .9 Name the 2 other spheres.
8.11 As Columbus’s fleet sailed westward the discrepancy between magnetic north and celestial north changed. Did it increase of decrease? Decreased, North magnetic pole deviates approximately 11 percent from the geographic pole. 8.12 Explain the difference in the orientations of the inclined compass needles in figure 8.18. Toward which cardinal direction is the observer facing? The needle of the compass dips downward in the northern hemisphere and upward in the southern hemisphere. 8.16 During which of these 5 geologic periods were Europe and North America most different in their positions with Earth’s magnetic field? Triassic
8.17 Place the 3 kinds of reefs in figure 8.26 in their order of succession from oldest first to youngest last. Fringing reefs are the oldest, the next oldest would be the barrier reefs, and the youngest reefs are the atoll.
8.18 What explains the shrinking of ocean crust as the crust moves away from volcanoes? As the ocean crust moves away from the volcanoes the shrink because there is lower temperatures. Once the volcanoes form them they begin moving away downward. 8.20 Does it appear in figure 8.29 that the reversals in Earth’s magnetic field are separated in equal periods of time, or are they random in their occurrences? They are random in their occurrences because for example, some periods they reversed 3 times, while in other periods they did not reverse at all. 8.21 What were the three observations that Vine and Mathews made about the stripes? 1. Directional trends- stripes tend to change all on the same direction.
2. Order of the color coding on sides of the ridges- the order of the colors on the side of the ridges corresponds to the color on the sea floor.
3. Widths of stripes compared to the duration of stripes-the wider the stripes are the longer the stripes lived. 8.25 Why doesn’t the South American plate descend beneath the Nazca plate? The Nazca plate is denser than the South American plate.
8.26 How many years will it be until Los Angeles and San Francisco are side by side? Approximately in 12.5 million years
8.27 What is the average rate of northward movement of India during the past 71 million years (in centimeters per year)? 15/71= approximately 2.12 cm per year
8.28 In centimeters per year, calculate the rate at which the Pacific plate is moving northwestern to the hotspot (which is marked by present day volcanoes). 50/5= 10 centimeters per year
8.30 Describe the direction of movement of the Pacific plate during the development of the volcanic islands that comprise the Seamounts. How has that direction changed? During the development of volcanic islands, the pacific plates used to move more northward, but due to the bend in the seamounts caused the plates to shift its movement more on the northwest direction.
Address the following in a 200-300 word summary:
Summarize the general principles and purpose of the lab.
Explain how this lab helped you better understand the topics and concepts addressed this week. Describe what you found challenging about this lab.
Describe what you found interesting about this lab.
Write your summary here:
This lab was very informative about plate tectonics I learn quite a bit of new information during this study. There were a few thing that I can remember studying during high school, such as continental drift and how continents formed from one single land mass called Pangaea. One thing that I found challenging was about the earth’s magnetic fields, I have never know how magnetic field could ever change. And during this lab I saw that it did not change once but multiple times throughout the years, I even had problems answering a few lab questions about the magnetic field. I also found this topic to be a little challenging, but also very interesting to learn about.
Another interesting thing I learned about in this lab was about how a compass can have discrepancy between the magnetic north and the celestial north. As the book says, this discrepancy made some members of the Columbus fleet gave up on their journey because they thought it was a sign. The thing I found to be interesting was how to calculate movement of the tectonic plates. Once again I really enjoyed this section of labs and look forward to the next set of lab assignments.