# Part 4—Create and Explore Computer-Generated Visualizations

## Step 1 – Make Seafloor Profiles in GeoMapApp

1. Use the magnifying glass to zoom in to an area that you'd like to explore.
2. Click the Grid icon to load the depth data for that region. This process can take about a minute, depending on how large an area you selected. When you see the Global Grids dialog box, minimize it (don't close it!).
3. Click the Profile icon in the Toolbar.
4. Click and drag a line across an area of the map and look at the resulting plot. Make and interpret several profiles so you can understand the graphical representation of the data.
5. Tips for Interpreting Profiles:
• Examine how the graph corresponds to the line you drew on the map image. Note where you start and stop each line you draw: the profile graph always shows the starting point of your line on the left and your ending point on the right.
• Read the values from the Y axis to interpret minimum and maximum depths along the profile.
• Consider the geologic features that are indicated by the graph.

## Step 2 – Make Contour Maps of the Seafloor in GeoMapApp

1. If necessary, zoom in to your area of interest and click the Grid button to load the depth data for that region (see Step 1, action #2 above).
2. Access the Grid Options dialog box (you may have it minimized) and click the Map Contours button (looks like a set of contour lines).
3. The Modify Contours? dialog box allows you to set the contour interval. You can accept the default settings by clicking OK or you can change the settings if you want to experiment.

## Step 3 – Choose a Topic to Investigate in More Depth

Choose one or more seafloor locations around the world and use GeoMapApp to create profiles and contour maps to study them in detail. For instance, you may want to:

• compare mid-ocean structures in the Atlantic with those in the Pacific or other oceans;
• look at differences on the seafloor around islands such as Japan, Hawaii, and Iceland;
• examine deep trenches at the edge of tectonic plates; and/or
• hypothesize about the geomorphology of the seafloor.

Once you've selected an investigation topic, follow the instructions above to produce profiles and contour maps of the locations you choose. Use the visualizations to consider what geologic and oceanographic processes have contributed to the observed topography.