Now that we are experts on Plate Motions, let's think about how Volcanic Island Chains work and how they can help to understand plate tectonics and ocean process.
The dots on the map below show locations of major Hotspots on Earth's surface.
I made the image below with Google Earth. It shows the Hawaiian Island Chain and the Emperor Seamount Chain. Follow the linear track to the northwest from the Hawaiian islands (yellow lines show island coastlines). The features that are not outlined in yellow are below sealevel; they're called seamounts. The Hawaiian chain connects to the Emperor Seamount Chain, which has a more northerly trend. The seamounts are extinct volcanoes. Each one of them was once located over the Hawaiian Hotspot.
Want to learn more?
- More information about hotspots, see "'Hotspots': Mantle thermal plumes."
NOTE: For this assignment, you will need to record your work on a word processing document. Please submitted in Pages, Word (.doc), or PDF (.pdf) format so I can open it.
- First, read this short paper. It's important background for mid-ocean ridges and the bathymetry around them:
- Macdonald, K.C. and P.J. Fox, The mid-ocean ridge, Scientific American 262:72-79, 1990.
- Download Google Earth and spend enough time with it to make an image of the ocean floor. In particular, look at the bathymetry around a mid-ocean ridge spreading center. Paste your image into a word processing document as noted above. Note that you should look at parts 3 and 4 before you complete this.
- In your document, comment briefly on how seafloor depth and morphology varies with increasing distance from a mid-ocean ridge spreading center. For example, I'm hoping you'll produce an image in part 1 that will tie-in with the article noted above. Think big, don't limit yourself to a few km from the spreading ridge; consider seafloor morphology at the scale of an entire ocean basin, like this example image of the Ocean Basin.
- Look at the Crustal Age Poster from NOAA. Download the image, take a screen shot, or use another approach to make a map of the ocean floor showing seafloor age. Add one or two other features to your map, and describe in a few sentences whether you could use a Web site like this in one of your classes. Paste your images into the word processing doc along with your comments.
- Save your document as either a text, Pages, Microsoft Word, or PDF file in the following format:
L2_activity2_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L2_activity2_eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Submitting your work
Upload your document to the "Lesson 2 - Activity 2" dropbox in Canvas (see Dropboxes folder under the Assignments tab) by the due date indicated on our Course Schedule.
See the grading rubric for specifics on how this assignment will be graded.