Map showing free-air gravity anomalies off the western coast of Africa Senegal (south of 15° north latitude) to Sierra Leone

This map is one of six in a series presenting marine gravity data off the western coast of Africa (fig. 1).  The data, collected by the U.S. Geological Survey (USGS) in 1987 in response to a request from the Defense Mapping Agency, are intended to improve gravity coverage where it has been insufficient or inadequate.  The information shown on this and the other three maps that cover the African coast represents a total of approximately 32,000 line kilometers of marine gravity data from Western Sahara south to Gabon.  This map includes data collected off the coasts of Senegal, Gambia, Guinea-Bissau, Guinea, and Sierra Leone from July 22 to August 20, 1987.