GEL 1 Discussion SectionExploring the SeafloorGoal: To visualize bathymetric features of the ocean basins so that their tectonic significance is more easily understood.Introduction: Seventy percent of the surface area of Earth is concealed from view beneath the world’s oceans. Most tectonic plate boundaries occur on the seafloor and are thus a challenge to recognize. Methods of mapping the seafloor include sophisticated updates of echo-sounding combined with massive computer firepower, and satellite measurements of variations in sea level due to differences in the gravitational pull of the solid crust beneath the oceans.Google Earth has pulled together all of the disparate sources of seafloor bathymetry into one easy-to-use package. Changes in the depth of the seafloor are shown in shades of blue: the darker the blue, the greater the depth.Tip: Be patient as you work through this exercise –learning a new tool like this requires experimentation. Earlier versions of this exercise have been vetted by several undergraduates for ease-of-use; it should take you less than an hour to complete. These instructions were created on a Mac, but they should be easily understood if working on a PC.The TAs will be lenient in their grading of your assignments. Just try to do your best.You should already have downloaded the desktop version of Google Earth at: https://www.google.com/earth/download/gep/agree.htmlAnd you should be somewhat comfortable with the controls after doing the previous discussion exercise.Creating a bathymetric profile of the Atlantic seafloorOpen Google Earth and make sure that all “Layers” along the lower left column are unchecked except for Terrain at the very bottom. Using the Add Path tool (outlined below), draw a line from Washington, DC (38.891°N,77.009°W –just cut and paste these latitude/longitude coordinates into GE’s search box) to the northwest coast of Africa (maybe around 22.242°N,15.757°W).Once you choose the Add Path tool, a window will pop up asking you to name the path. Call it Atlantic Profile or something similar. Then, while in the window, go to “Altitude” and choose “Clamped to sea floor.” The name of the Path will show up in your “Places” box along the left column.
INSTRUCTIONS
Profile, make a path/profileperpendicular to the Marianas Trench, passing close by the Challenger Deep. The profile doesn’t have to be too long, maybe a 1000 miles (1600 km) or so.By moving your cursor along the profile, what is the maximum water depth on your profile? (mine was ~33,000’ or 10,000 m) What is the approximate width of the trench? (mine was ~70 miles or 110 km) Take a screenshot and call it YourLastName_Pacific. Submit that image (with that file name!) to Assignments as part of the exercise. No need to label.Exploring the seafloor on your ownWander the world seafloor with GE until you find someplace that you think is interesting. Maybe the Caribbean Sea, or the Arctic Sea, or the California continental margin, or the South China Sea, or the Ross Sea off Antarctica, or anywhere you want. Choose a region, take a screenshot and label it YourLastName_YourRegion (e.g., Smith_ArcticSea). See if you can identify any significant seafloor features (e.g., underwater volcanoes, deep trenches, mid-ocean ridges, fracture zones, abyssal plains, continental shelves and slopes). Label any features that you can and submit the image to Assignments.