The Puzzling Plates Part I. Follow the steps below while taking notes in your science notebook.

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1 Procedure Follow the steps below while taking notes in your science notebook. 1. On the table is a pile of cardboard puzzle pieces. Work with your team to assemble the puzzle. The edges of the completed puzzle will be straight. 2. Now, think back to the previous activity, Introduction to the Seafloor. How do the shapes of these puzzle pieces relate to the seafloor? a. Identify the puzzle piece that represents the portion of the Pacific Ocean that you traced previously on the ocean floor map. Recall the seafloor features that nearly encircled the Pacific Ocean (what are they?). Hold up the puzzle piece so your teacher knows you are ready to continue. 3. Your teacher will now provide you with a seafloor map that is the same size as the puzzle. Lay the map next to your puzzle. a. Lay the puzzle piece you selected in number 2 on the appropriate part of the seafloor map. How do you know where to place it? Confer with your team- mates and agree on the location, using the knowledge you gained from the previous activity. 4. Find and place on the map other puzzle pieces that lie completely within the Pacific Ocean and contain no continents. Be sure you do not include the puzzle pieces that would cover the continent of Antarctica. a. How many pieces are found in the Pacific? Describe the seafloor and continental features that surround each of these plates. Overheads-1

2 b. The Pacific Ocean should now be almost completely covered with puzzle pieces. Relate the shapes of the pieces to the distribution of earthquake epicenters observed in the Quakes and Plates activity. The largest puzzle piece you have placed on the map can now be referred to as the Pacific Plate. (Note: Plate names will all be bulleted and in bold font so you will be able to review them later.) The cardboard piece, however, is only one layer of the plate. It represents the uppermost portion of the earth s mantle, called the upper mantle. Plates that do not include continents are called oceanic plates. The Pacific Plate is the largest oceanic plate on Earth. The other Pacific oceanic plates you have in the puzzle are adjacent to (border) the Pacific Plate: Philippine Plate (to the west) Nazca Plate (to the southeast) Cocos Plate (to the east) Juan de Fuca Plate (the small plate to the northeast) 5. The Pacific Plate 1) is an enormous oceanic plate, 2) nearly covers the entire ocean basin, and 3) lies completely within the ocean basin. Move now to the Atlantic Ocean. Using the three criteria listed above, can you now find an Atlantic Plate? If not, go to number 6. Overheads-2

3 6. If you had difficulties finding a large oceanic plate that fits entirely within the Atlantic Ocean basin, don t worry. There is no Atlantic Plate! (Sorry, but you needed to discover that for yourself. That s the only trick question, rest assured.) Did you find any plates with no continent included? There are only two small oceanic plates in the Atlantic: Caribbean Plate (south of N. America) Scotia Plate (southeast of S. America) Locate them and place them on the map. 7. Since there is no Atlantic Plate, cover up the Atlantic Ocean with the puzzle pieces (plates) that contribute to its seafloor. Because each of these plates has significant areas covered by continents, we refer to them as continental plates. Again, omit the Antarctic Plate (the reason why will soon be explained). Note: Remember that the earth is a sphere, so puzzle pieces may continue to the other side of the puzzle. a. These plates are named for the continents included on them. With your group, be sure to identify each of the following: North American Plate Eurasian Plate African Plate South American Plate. b. What seafloor feature is related to the four major pieces that cover the Atlantic Ocean? 8. Move now to the Indian Ocean. Place the puzzle pieces (plates) that comprise the Indian Ocean. Once again, omit Antarctica. One piece includes India, and also stretches eastward to include Australia. This plate has several names and most geologists agree that it is Overheads-3

4 currently breaking apart into two plates. Here we will simply refer to it as the Australian Plate. 9. The oceans on your map should almost be covered except for the southern portions of the Pacific, Atlantic, and Indian Oceans. Finally, you may add Antarctica to the map! This continental plate is called the Antarctic Plate. This plate was saved until the end because it only appears to be an enormous plate. Because you are looking at a 2-dimensional map view of a 3-dimensional planet, the polar regions are grossly exaggerated. a. Examine the classroom globe to see approximately how large the Antarctic Plate is relative to the Pacific Plate. This plate is mostly continental (not all of the continent is shown on the puzzle) and it is surrounded by a ridge that connects the three oceans. 10. There should be only one small continental piece remaining, the Arabian Plate. Place this piece on the map to complete the puzzle! How many plates do you have? The plates included in this puzzle are only the larger of Earth s plates. There are several minor plates that are too small to illustrate using this model. These 14 plates (or 15 if you break apart the Indo- Australian Plate) are considered to be the major plates of the Earth. Many of these major plates include much smaller micro-plates. 11. On a sheet of paper, make a table (or chart) that lists the four major ocean basins, and the oceanic plates and continental plates Overheads-4

5 that are part of each. If a plate contributes to more than one ocean basin, be sure to include it wherever is necessary. The layer of Earth that you have assembled is the upper mantle portion of the lithosphere. The lithosphere is comprised of the upper mantle and the overlying crust. All of the lithosphere is relatively cold rock, as compared to the deeper mantle and core. So, now you have a map of the earth s upper mantle. The earth s surface layer is still missing the crust. Your teacher will now provide you with the crust layer puzzle pieces. The crust is represented by cut pieces of another copy of the same map you used earlier (which is now under your puzzle!). 12. Place all the crust pieces in their appropriate locations on the puzzle to complete the lithosphere. Each lithospheric plate (another term for plate) is now accurately made of upper mantle (cardboard layer) and crust (top map layer). Remember that a plate is comprised of the crust and upper mantle. A plate is a broken piece of the lithosphere. Lithosphere = Crust + Upper Mantle 13. Using your previous observations from steps 2-12, write the name of each plate on a label (or Post-It Note) and affix it to the appropriate plate. If a plate extends to the east-west edges of the puzzle and map, remember to label the plate piece on the other side of the world! Overheads-5

6 14. Explore the various plates individually by removing them (both crust and mantle) one by one from the puzzle and examining the seafloor features along the plate s edges. a. Make a table (or chart) that lists all of the seafloor features found along the edges of the following five plates: Pacific Plate Nazca Plate South American Plate African Plate Indo-Australian Plate Summarize your observations and discoveries by answering the questions on the next page. Overheads-6

7 Questions Use your observations of the Earth s lithospheric plates and their relationship to seafloor features to answer the following questions. Your teacher will provide information of how to format your answers. 1) What are the layers included in the lithosphere? What is a lithospheric plate? 2) Explain what is meant by the terms oceanic plate and continental plate. 3) In terms of the types of plates found (oceanic plate vs. continental plate); compare the Pacific Ocean basin and the Atlantic Ocean basin. 4) Is the Indian Ocean basin more like the Pacific Ocean basin or the Atlantic Ocean basin? Justify your answer, using your answer to the previous question. 5) What is the dominant type of seafloor feature associated with the plates that are included in the Atlantic Ocean basin? What type of plate (oceanic or continental) is found along this seafloor feature? List the four major plates. 6) What kind of plate is the Antarctic Plate? What is the dominant seafloor feature that surrounds this plate? Overheads-7

8 7) What is the dominant type of seafloor feature associated with the northern and western edges of the Pacific Plate? Examine the edges of the adjacent plates - those that touch the Pacific Plate. Is there oceanic crust or continental crust bordering the Pacific Plate? Write a short paragraph, comparing this area with the eastern edge of the Nazca Plate. 8) Select one of the 4 plates listed below from the puzzle. Write a story that takes the reader on a tour around the perimeter of the selected plate. Imagine that you are operating a submersible (a manned underwater vehicle with viewing capabilities) just above the seafloor. Describe the features you encounter along the way. Use the World Wide Web and other resources available to find pictures of different seafloor images of mid-ocean ridges, trenches, fracture zones and seamounts to aid with your descriptions. Nazca Plate Cocos Plate Juan de Fuca Plate Indo-Australian Plate Caribbean Plate Overheads-8