annotated-Kami20-20worksheet plate tetonics
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Apr 3, 2024
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Ocean Discovery Journal Plate Tectonic Boundaries & Seafloor Spreading Follow the instructions below and use these sheets to record your answers to the Ocean Discovery Plate Tectonic & Seafloor Spreading exercise. Scientists commonly use multiple tools, databases, and sources of information. This activity similarly uses two different web map-tools. Digital Maps of Global Plates
and Global Background Seismicity
are provided online by California Institute of Technology’s Seismological Laboratory. The Earthquake Viewer is provided by the IRIS consortium. You need to complete ALL sections of the exercise recording your answers on this worksheet as you go. These answer sheets should be added to your Ocean Discovery Journal
for review and later assessment. You may also use the Notes
section at the bottom to record other thoughts or questions you may have that arise during your completion of this exercise. Discovering Plate Boundaries Lithospheric Plates & Plate Boundaries Step 1> Instructions Open> Tectonic Plate Map http://tectonics.caltech.edu/images/maps/plates.pdf
Take a moment to familiarize with the map and use the zoom feature to look more closely. The map shows the word’s plate boundaries, using colors to differentiate between divergent, convergent and transform margins. Study the map noting the general location of major plate boundaries. Step 1> Questions 1.
Place in order from greatest length on the Earth’s surface to least, the three types of plate boundaries. When Wegener devised the Continental Drift hypothesis he envisioned the continents moving either over or through the ocean basins. This was one of his greatest difficulties. Geophysicists correctly pointed out that the frictional resistance in such a scenario would be impossibly large and the rocks would simply shatter. Discovery Activity Plate Tectonics
Ocean Discovery Journal
Plate Tectonics
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Examine the relationship between continents and plates by looking at the map you created. 2. In general, do continental shorelines coincide with plate boundaries? 3. Do lithospheric plates tend to have both continents and oceans imbedded within them? Now look at the coastlines of North America. Continental margins that are associated with a plate boundary are referred to as “active margins.” Those coastlines that are not associated with a plate boundary are referred to as a “passive margin.” 4. Of the Pacific, the Gulf, and the Atlantic Coasts, which are passive and which are active margins? If any are active, list the types of plate boundaries that are present. Earthquake Depth Step 2> Instructions Open> Global Seismicity Map https://www.nsf.gov/news/mmg/media/images/global_seismicity_h.jpg Examine the world seismicity map. Note the key indicating location of epicenters for earthquakes and focal depths. Note that the tectonic map and the seismicity maps are similar but vary depending on the focal depths of the various earthquakes that are plotted and the time period of seismicity that is displayed. Step 2> Questions 5. In general, how do zones of seismicity compare to plate boundaries? Look at areas of the Northwestern Pacific Basin. This area is part of the Ring of Fire
of the circum Pacific region. It is dominated by subduction zones. Examine the pattern of seismicity across the subduction zones. 6. Describe the seismicity above subduction zones. How does it compare to the seismicity seen along divergent and transform margins?
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7. Look carefully across the Japanese Island arc. Here the Pacific Plate is diving under Japan. Do you notice any trend in seismicity across the island arc? Explain. Volcanism Step 3> Instructions Open> Global Volcanism Map https://worldinmaps.com/wp-content/uploads/2020/05/volcano-world-map.jpg Now click on Global Volcanism Map to see the plot of active volcanoes (red triangles). Study the patterns of volcanism that appears on the map. Step 3> Questions 8. How does the distribution of volcanoes compare to plate boundaries? 9. Describe the pattern of volcanism in the area of the circum Pacific region commonly referred to as the Ring of Fire. Sea-floor Spreading Mid-Atlantic Ridge Step 4> Instructions Open> Tectonic Plate Map http://tectonics.caltech.edu/images/maps/plates.pdf
Using the Tectonic Plate Map
, look at the various plate boundaries. Look at the Legend
and note the color code used for each type plate boundary. Examine the divergent plate boundary in the middle of the Atlantic Ocean and answer the following Question. Step 4> Questions: 11. How does the shape of the plate boundary compare with the shape of the coastlines of South America and Africa; with North America and Europe? 12. Does this relationship support what you understand about the breakup of Pangaea? Explain.
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Ocean Discovery Journal
Plate Tectonics
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Ocean Floor Age Step 5> Instructions: Open> Age of the Ocean Floor https://ngdc.noaa.gov/mgg/image/images/g01167-pos-a0001.pdf Your map will now show the seafloor with ages marked by different colors. The legend on the bottom shows the relationship of color to actual age of the rocks of the seafloor. In general, the darker “cooler” colors are older and the brighter “hot” colors represent younger seafloor. Examine the relationship especially within the Atlantic Ocean Basin. Step 5> Questions: 13. Where are the youngest rocks in the Atlantic Ocean? 14. Where are the oldest Atlantic rocks? 15. Does this support the Vine-Matthew-Morley hypothesis of seafloor spreading? Explain. 16. Look at the pattern of ocean floor ages for the North Atlantic and South Atlantic Ocean Basins. During the break up of Pangaea did the North Atlantic or South Atlantic Ocean Basin open first? How can you tell? Acknowledgements The digital maps of Tectonic Plates and Global Seismicity are produced and provided by the California Institute of Technology Seismological Laboratory and is supported by the National Science Foundation. The map of Global Volcanism is produced and maintained by WorldMaps.com. The map of Ocean Floor Ages was produced and provided by the National Oceanic and Atmospheric Administration (NOAA). About the Earth Discovery Project The Earth Discovery Project is a collaborative effort to integrate hands-on discovery-based learning with modern research tools in undergraduate geoscience education. The approach is to develop and disseminate a comprehensive set of learning resources and experiences supporting systemic educational reform. The logo of the Earth Discovery Project portrays the earth as a three-dimensional puzzle. The globe used in the logo is from NASA’s Blue Marble Project
. The Blue Marble
is a unique view of the earth, which integrates numerous data sets to construct a “true-color” three-dimensional globe.