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Geology
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Feb 20, 2024
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GLG 110 Natural Disasters Name: __________________________ Investigation 5 Plate Tectonics
Instructions: In this lab, you’ll be investigating plate tectonics using the web version of Google Earth
: https://earth.google.com (
Several browsers are supported, but switch to Google Chrome if you have trouble.)
Google Earth is not just a map of the globe with satellite imagery. It allows you to display any kind of geographic data in separate layers that can be turned on and off individually on the left side of the screen by clicking “Projects” . To get started, you will need to download the geology_layers_combined_v3.kmz
file posted with this assignment in Canvas. To load this into Google Earth, click the projects button on the left and click “Import KML File”, and select the file you downloaded. After a few moments, the layers will appear. Click the small arrow to the left of “Geology Layers” to view the layers, and click the eyeball icon to the right of each one to enable or disable it on the map. 1.
First, make sure that the “Plate Boundaries” layer is the only geology layer that is currently visible. As you’ll see, convergent boundaries are shown in blue, divergent boundaries in green, and transform boundaries in red. Does the mid-ocean ridge (divergent boundary) in the Atlantic Ocean connect to the mid-ocean ridge in the Indian Ocean? Explain/describe. I would say yes because it appears that the mid ocean ridge travels under Africa and comes up into the Indian ocean. 2.
Examine the elevation profile below (created with the desktop version of Google Earth) for the path across the Atlantic shown if you turn on the “Question 2” layer. Elevation is shown on the left in feet above/below sea level (if you can read it) but each line marks 2,500 ft and the top-most line is roughly 0 ft. a)
Where is the mid-ocean ridge? (Label/draw to show, or describe using the numbers on the x-axis.) The mid ocean ridge is in between 1750mi and 2750mi, b)
What is the approximate height of the mid-ocean ridge above the lower seafloor around it? (Your answer should not
be a negative number.) It is approximately 10,500ft .
3.
Where can you find an example of an ocean-ocean convergent boundary? An example of oceanic to oceanic convergent boundary is the Aleutian Islands.
4.
Click the “Search” button ( ) on the left and type in these coordinates: 38.086, 38.278 a)
What type of plate boundary is there? A convergent boundary. b)
What country is this location in? Turkey 5.
Describe how the plate boundary changes along the West Coast of the United States, from Southern California up to Washington. Along the west coast is a transform boundary. One plate is moving north and one plate is moving south. 6.
Look around just north of Los Angeles. How is the location of the San Andreas fault visible on the landscape? You can see the drop off in the ocean miles out from shore, you can also see many islands as a result of the horizontal shifting. 7.
Open “Projects” again and turn on the “USGS Earthquakes” layer. This will show you a collection of earthquakes in 2016 and 2017 that were magnitude 4.5 or higher. a)
Are most earthquakes along plate boundaries? Yes most are along plate boundaries. a)
Are all
earthquakes along plate boundaries? No, not all earthquakes are along boundaries. 8.
Note that the color of the dots marking each earthquake corresponds to the depth
of each earthquake below the Earth’s surface. (Close the “Projects” window and look top left for the legend.) Look around the world at plate boundaries with earthquakes. a)
Which type of plate boundary hosts the deepest earthquakes? It appears that it is worst at transform boundaries. b)
Why do you think this is? I think this is because it creates the most friction. 9.
Now turn on the “Seafloor Age” layer. (Feel free to turn off the earthquakes layer to make it easier to see.) Like the map we saw in lecture, the color scale shows the age of the ocean crust—how long it has been since that ocean crust formed at the mid-ocean ridge.
Compare the Pacific and Atlantic Oceans. Judging from the seafloor age data, which mid-ocean ridge is spreading faster? Explain how you can tell. The pacific mid ocean rage is spreading faster because the colors are bunched together as tight as the mid ocean range in the Atlantic. 10.
Look at the seafloor off the coast of Oregon and Washington. Find the divergent boundary, and compare the seafloor ages on either side. Why don’t you see more colors (that is, older seafloor) between the divergent boundary and the coastline of these two states? I believe this is because between these two states are a transform boundary and the rest is a divergent boundary. 11.
Turn on the “Question 11” layer to see a line in the ocean west of Central America. The length of this line is 2,616 miles. Using the seafloor age map, calculate the average rate at which this seafloor was created in miles per million years
. There is 15,290-19,113 years per mile on this line. 12.
Turn off the seafloor age layer. Turn on the “Volcanoes of the World” layer. (And if you turned off the earthquakes layer previously, turn that back on, as well.) Look around the edges of the Pacific Ocean. a)
Why is this often referred to as the “Pacific Ring of Fire”? Because there is a large ring around the pacific ocean of volcanos. a)
What is the plate tectonic explanation for your answer to #12a? (That is, in plate tectonic terms, what is
the Pacific Ring of Fire?) 13.
Turn on the “Question 13” layer to see a line running across the coast of Washington. Using the elevation profile below to help you, draw a cross-section conceptual model of what the tectonic plates beneath this line are doing. (
You can use drawing tools on your computer or attach a photo of a separate page.
)
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14.
Where is the lithosphere thicker: the boundary at the Himalayas (coordinates 27.96, 84.39) or in the middle of the seafloor (coordinates 14.30, 64.18, for example)? Coastline