1. Map showing free-air gravity anomalies off the western coast of Africa : Senegal (south of 15⁰ north latitude) to Sierra Leone Yale Public content 1990. 2002-06-01T04:00:00Z. 2002-06-01T04:00:00Z. Geological Survey (U.S.). The Survey ; For sale by Map Distribution. English. Public. Africa, West and Atlantic Coast (Africa).