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Assignment Week 4
Use the figures in your textbookor on the lecture slides to answer the following plate-tectonic questions:
1. Which lithosphere plate contains most of the United States?
2. Name a part of the United States that is not on that plate. On which plate is it?
3. Name all the plates that meet at the Mid-Atlantic Ridge.
4. Locate the Nazca Plate on the tectonic plate map in your textbook or on the lecture slides. Which plates does it border, and what kinds of plate boundaries does it have?
5. Rocks about 180 million years old can be found off the eastern coast of the United States and off the coast of Africa. The distance between Africa and the United States is about 3842 miles. New rocks are forming on the ocean floor right now along the Mid-Atlantic Ridge, about half way in between Africa and North America. Assume that the 180 million year old rocks started at the Mid-Atlantic Ridge and have traveled to their current locations at a constant rate since that time. How fast have the rocks off of the United States east coast moved? Report your answer in miles per million years, then convert your answer to centimeters per year (Hint: There are 2.54 cm in 1 inch and 12 inches in 1 foot. There are 5,280 feet in one mile.). Check if your answer fits with what we have learned about the rates of tectonic plate movement.
6. Which plates meet in the Himalayas region? What kind of plate boundary is it? What type(s) of crust is/are on either side?
7. The figure below shows a section of our plate-tectonic map centered on the Juan de Fuca Plate in the northwest of North America. Sketch and label a cross section (marked by the line A-B, extending from the Pacific Plate across the Juan de Fuca Plate into the North American Plate) of the plates through which it runs, their likely geologic features (rise of magma and its origin, volcanoes, earthquakes, …), and how the plates are moving relative to each other. Use the lecture slides and your textbook for reference. (Hint: A cross section is a vertical view of the profile marked in the picture – as if you were viewing at this area sideways and also seeing what’s going on beneath the surface.)
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