Going Further

Variations

Now that you have used GeoMapApp to explore images and data from the East Pacific Rise, the following data sets may be help to further test the hypotheses developed in Part 4. You may also be interested in exploring geochemical data, gravity measurements, seafloor ages, and much more that is available through the GeoMapApp data portal.

More images from hydrothermal vents at the EPR

GeoMapApp provides access to the data from each Alvin dive at the East Pacific Rise, including images that are georeferenced (mapped to a location) along the path of each trip. In Parts 3 and 4 of the chapter, you worked with a subset of twenty images, but the full set of thousands of images is available to view and explore.

Show me how to access these data

Hide

1. Use the Focus Sites pulldown menu to select NSF Ridge 2000 Program > East Pacific Rise at 9 North > Bottom Images > EPR: 9_50N.
2. This selection loads a shapefile into the GeoMapApp layer manager and main window, and opens a new window called Shapefile Manager.
3. To zoom the main window to the appropriate scale for viewing the tracks of all the Alvin dives, click on the zoom button in the Shapefile Manager.
4. Each black line on the main window represents the path of a particular dive, and is identified in the Shapefile Manager with a file name and metadata. Click on a path in the main window, and its associated file is highlighted in the Shapefile Manager. Click on a file in the Shapefile Manager, and its associated path is highlighted in the main window.
5. Once a path and file are selected, click on the Open Object button in the Shapefile Manager. A new layer of images has now been loaded into the Layer manager.
6. Click on the Open Object button a second time, and a new window associated with the Shapefile Manager is opened, where you can view all the images of the seafloor taken on that particular Alvin dive.
7. As you scroll through the images using the arrows in the image window menu options, note that the location of each image is identified on the path of the Alvin dive in the main window. Two images have been taken at each location, and can be selected by choosing Camera 1 or Camera 2 in the image window menu options.

Geochemical data from the EPR

The concentration of unique chemicals available at hydrothermal vents provide the energy and nutrients that support the entire community of organisms seen in the Alvin images. You may wish to explore hypotheses about the location and availability of various elements, compounds, and isotopes at the East Pacific Rise, using the PetDB database accessible through GeoMapApp.

Show me how to access these data

Hide

1. Use the Focus Sites pulldown menu to select NSF Ridge 2000 Program > East Pacific Rise at 9 North > Tables > Volcanic Glass Chemistry from PetDB - EPR.
2. As before, you will probably want to reduce the size and adjust the color of the symbols that indicate the locations of the Vent Locations and Image Locations data sets in your GeoMapApp window. Select Configure from the Data Tables Tool Box and adjust these display features as needed.
3. The data from PetDB can be inspected directly in the data table, or can be mapped or graphed using a variety of tools in the Data Tables Tool Box:
   • One technique you might try is to select Color by Value from the tool box menu and choose an element, compound, or isotope that you want to investigate. The color of each samples' location symbol in the main window will depend on its measured value. You could use the color patterns to identify trends in the concentration of a particular element, compound, or isotope as you move around seafloor at the EPR.
   • A similar technique is to select Scale by Value from the same menu. Instead of changing the color, the size of each symbol will be change depending on its measured value.
   • Select Graph from the tool box menu to create scatter plots graphing the measured values of two elements, compounds, or isotopes against each other. (You may need to use the configure button to change the size of each symbol back to 100% in order to see the points plotted on the graphs.)
4. These techniques allow you to develop and test a wide variety of hypotheses about the location and availability of chemicals that underlie the EPR ecosystem.

Additional Information

Learn More About the Alvin

The deep-submergence vehicle (DSV) 'Alvin' is a human-occupied submersible, operated by the Woods Hole Oceanographic Institution (WHOI), that can carry three people to ocean depths of 4500 m (approximately 3 miles). On an expedition to the East Pacific Rise, Alvin will typically be deployed from the research vessel (R/V) Atlantis at 8 a.m. with a pilot and two scientists, who will travel about 90 minutes to the seafloor. While on the seafloor the scientists use the equipment onboard Alvin to see what is hidden in the darkness. This equipment includes several video and still cameras as well as powerful artificial lights. They record their data with computers that record information about the depth, temperature, and location of the observations and samples that are collected. The scientists work until 3 p.m., when they will release the last dive weights and slowly ascend to the surface of the ocean to be recovered to the deck of the ship. After an Alvin dive, scientists study the images and samples and compare their observations to these metadata (sometimes referred to as "data about data")—such as depth, temperature, and location—that can better inform the scientists about their observations.

You may wish to read more information about Alvin and other submersibles in the National Deep Submergence Facility at Woods Hole.

Related Case Studies

Other EET chapters that utilize GeoMapApp as a tool or life in the ocean as a data source include the following:

• Exploring Seafloor Topography — Use digital elevation model data and bathymetry to produce profiles of the world's oceans—exploring canyons and mountains and plate boundaries below the ocean's surface.
• When is Dinner Served? Predicting the Spring Phytoplankton Bloom in the Gulf of Maine — Use ocean Buoy Data and MODIS Images to learn about conditions that influence the spring phytoplankton bloom.