Visualize bathymetric features of the ocean

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°N77.009°W –just cut and paste these latitude/longitude coordinates into GE’s search box) to the northwest coast of Africa (maybe around 22.242°N15.757°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. Now with the Path name highlighted in Places go up to Edit and choose “Show Elevation Profile.” (Right-clicking will work as well.) You’ll see a bathymetric profile of the seafloor between the two endpoints that should look something like the image below.As you move your cursor along the profile at the bottom in GE you can track your location along the path on the map above. Based on what you know from the GEL1 lecture what are the two shallow regions adjacent to the continents? (continental margins) What is the jagged somewhat symmetrical feature in the middle of the profile/path? (Mid-Atlantic Ridge) What are the deepest parts of the profile called and what is their depth? (abyssal plains ~17000’ or ~5200 m)Take a screenshot and call it YourLastName_Atlantic. Label each of the different bathymetric features directly on the image (either with your computer or by hand) then submit that image (with that file name!) to Assignments as part of the exercise.Visiting the deepest point on EarthType “Challenger Deep” into the search box and let GE take you to the deepest point on Earth. (Click the “N” at the top of the upper compass wheel to keep North at the top of your view. Hold and rotate the “N” around the compass to see different perspectives.) Begin at an eye altitude around 2600 miles (4200 km) (It doesn’t have to be exact just high enough so you see the bigger picture). Where are you on Earth? (western Pacific Ocean)Zoom in close enough to explore the dark arcing band in which the Challenger Deep is located. It’s called the Marianas Trench and it parallels the Marianas Island chain. Can you guess why the deep ocean trench has an arcuate shape? Think of cutting an apple while holding the knife at relatively flat angle to the apple’s surface. Whatshape of cut do you create on the surface of the apple?Using your cursor to explore around the marker for the Challenger Deep what is the greatest water depth you can find? (Alternatively look it up on Google.) (~ 36000’ or ~11000 m) Using the instructions above for using the Path tool and creating an Elevation 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 ~33000’ or 10000 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.

Requirements: google earth pro(screen shot) | .doc file