complete answer sheet
Unit 10 Lab exercise: The Dynamic Planet Instructions and Answer Sheet This exercise will introduce you to Earth’s endogenic systems, patterns of plate tectonics, and the geologic history of our planet. After the lecture and completing these exercises, you should be able to: Describe Pangaea and its breakup and relate several physical proofs that crustal drifting is continuing today; Portray the pattern of Earth’s major plates and relate this pattern to the occurrence of earthquakes, volcanic activity, and hot spots. Download the Unit10_dynamic.kmz file and open it in Google Earth™. A new folder named “The Dynamic Planet” will show up under Temporary Places. This folder has multiple sub-folders that contain the placemarks we will use today. Double click on the Earth’s Tectonic Plates placemark and make sure that its box is checked. For best viewing of the faults turn off the Borders and Labels layer and the Roads layer (under the Layers tab on the bottom of the left hand side window). You should zoom into the San Andreas fault. Take some time to pan around and look at the fault features. Double click on the Age of the Ocean Floors placemark and make sure that its check box is checked (to make it visible). Also turn on the Earth’s Tectonic Plates layer. Answer the questions in the spaces below. 1. Where is the oldest oceanic crust? 2. What type of plate boundary is the oldest crust near? 3. Where is the youngest crust? 4. What type of plate boundary is the youngest crust near? 5. Compare the rate of spreading along the mid-Atlantic ridge at 20° S, 12° W to the rate of spreading in the Pacific at 20° S, 112° W without calculating the exact rate. Hint: How wide is the red-colored region in km in each ocean? This is the active spreading zone (youngest rock formation). Which one has a wider spreading zone within the same timeframe? 6. The red region is at the most 9.5 million years old. Calculate the spreading rate for the Atlantic basin in cm/year? 7. What is the spreading rate for the Pacific basin in cm/year? 8. What general conclusions can you draw from the relationships between the types of plate boundaries and the ages of crust? Keep the following layers turned off: Earth’s Tectonic Plates layer and the Age of the Ocean Floors layer. For the most recent earthquake data, you need to update the USGS Real-Time Earthquakes placemark. To do this, find the “USGS Real-Time Earthquakes” folder, expand it and go all the way in through expanding the next layer “Real-time Earthquakes” and reaching the final folder “Earthquakes”. Right-click on this folder name, go to “Properties” or "Get Info" depending on your Google Earth version, replace the original URL link with this new one: https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/1.0_week_age_link.kml To view all volcanoes in the Quaternary, you need to follow the link below to download this file. Once it is downloaded, double-click to open in Google Earth: https://volcano.si.edu/ge/GVPWorldVolcanoes.kml For viewing volcanic activities in the past week only, go to the following URL and download this one: https://volcano.si.edu/news/WeeklyVolcanoGE.kml With these multiple layers turned on, you should have a comprehensive view of the relationships between plate boundaries, earthquakes, and volcanoes. For example, check the little triangle to the front of the folder USGS Real-Time Earthquakes to expand it, expand Earthquakes folder under it, and then the USGS Magnitude 1.0+ Earthquakes, Past Week folder and one more until you see a set of folders named by Magnitudes. You can expand any of the magnitude folders and the list of earthquakes that recently happened with that magnitude will be listed. You can double click one to zoom it the region to see the patterns. Answer the following questions in the spaces below. 9. In general, where do you find the most concentration of earthquakes? 10. Locate one place with a good concentration of earthquakes, write down the latitude and longitude here. 11. Why do you see the concentration of earthquakes here? After you examine the earthquakes, you may check off the box next to “Earthquakes” (note: only the “Earthquakes” sub-folder and not its parent folders!) to turn off this layer for better view of other layers. 12. Double click on the Andes Mountains placemark. Navigate around. What kind of boundary is offshore? 13. What is the speed of movement of the Pacific Plate where it is subducting under the South American Plate? (look for the white arrow and text) 14. Zoom to the Lesser Antilles placemark. How rapidly is the Atlantic Plate subducting under the Caribbean Plate? 15. Double click on the Rift Valley of Africa and the Ethiopian Plateau placemark. What type of plate boundary are these volcanoes located near? 16. Double click on the Scotia Plate placemark. Among all of the last four placemarks you examined, which plate is moving the fastest and how fast is it moving? 17. Explore around the globe to locate more white arrows. What is the fastest movement speed you found? (Note: you need to maintain a certain zoomed-in level to be able to read the speed) 18. This fast speed is due to the movement of _____________plate? Check on both Volcanoes layer you downloaded before. Explore the patterns of Volcano distributions around the world. (Note: you need to be at a certain Zoom level to see the volcanos). 19. Where in general do you see the most concentration of volcanos? What is the geological process that resulted in these volcanos? 20. Are there volcanoes that are not located near a plate boundary? What are the names of a few of these volcanoes and the plates they are on? When you quit Google Earth, you may discard the loaded layers if prompted.