Bathymetric Maps
Bathymetry is the measurements of water depths. One way to visualize the seafloor is by using a contour map. Contours are lines drawn connecting points of equal depth. It’s like “connect the dots” but with a twist. The lines are called isobaths, a line on a map that connects all points having the same depth below sea-level. Watch the first 6 minutes of this video, How to Draw Contours http://www.youtube.com/watch?v=L6FbV0LiA_k. The twist is that the depths for the isobaths may not be marked on the map; you’ll have to make an educated guess.
- Looks like the boat captain didn’t finish drawing this bathymetric map. He managed to draw the 500-foot isobar. Draw the 485, 490, 495, 505, and 510 feet isobars.
Figure 1. Bathymetric map with the 500-ft contour line. - This map contains a bunch of soundings. Complete this contour map using a contour interval of 10 feet starting at 80ft, 90ft, … to 130 ft. For now, ignore the line connecting points A and B.
Figure 2. Soundings map with points A and B. - Once you have drawn all the isobars, take the edge of a sheet of paper, and line it up with the gray dotted line. Mark the letters A and B on your paper. For every spot an isobar touches your paper, make a tick mark and write down the depth.
Figure 3. A pirate constructing a contour profile map of the ocean floor. - Take the sheet of paper, line it up with the graph paper and plot the depths on the graph below.