EAS 100
Ocean Basin Depth Profile
(Trans-Atlantic Ocean Depth Profile –
Cape Hatteras, North America to Cape Blanc, Africa)
Name: _________________________
Objective:
Plot a bathymetric (ocean depth) profile across the Atlantic Ocean to examine the typical shape of the ocean basins. This exercise also provides experience with graphing and concepts of scale.
Procedure:
The table given on the attached page contains depth data for a transect across the Atlantic Ocean from Cape Hatteras, North America to Cape Blanc, Africa. Plot the 61 distance and depth points on the attached graph, then connect the dots to form a bathymetric profile or ocean basin topography profile. Note that the distance scale is in kilometers and the depth scale is in meters. Thus, the depth data are vertically exaggerated (by a factor of 200) which enhances the subtle features of the ocean basin topography. A plot at true (1 to 1) scale will be provided later to show the actual topography. Vertical exaggeration is useful to display profile data when the horizontal extent of the data is very large and when the profile is relatively smooth. The data that are given in the table are sampled at a large interval (100 km between data points) and, thus, the bathymetric profile is only a rough approximation of the true ocean basin topography. However, the main features of the ocean basin are visible on the graph. For additional background information, refer to pages 239-244 of Lutgens and Tarbuck (2002).
Questions:
1. On the graph, label the following features of the ocean basin: continental slope, abyssal plain, mid-Atlantic ridge.
2. What is the approximate ocean depth at the mid-Atlantic ridge and the relief of the ridge (difference in depths, or elevations, between the top of the ridge and the adjacent, relatively flat ocean bottom)?
Ocean depth at mid-Atlantic ridge __________
Relief (difference in ocean depth between the ridge and the abyssal plain)
Of mid-Atlantic ridge __________
3. What is the approximate slope of the west flank of the mid-Atlantic Ridge (measure the difference in ocean depth along the profile between about 2200 km and 3200 km distance and divide by the difference in distance, 3200-2200 or 1000 km. Be sure that both measurements, differences in depth, and distance, are in the same units, either km or m. the resulting number will be the slope expressed as a ratio. (The slope can also be given as a percent or as an angle.)
Approximate slope of the west side of the mid-Atlantic ridge __________.
