As part of a program undertaken cooperatively by the Liberian Geological Survey (LGS) and the U. S. Geological Survey (USGS), under the sponsorship of the Government of Liberia and the Agency for International Development, U. S. Department of State, Liberia was mapped by geologic and geophysical methods during the period 1965 to 1972. The resulting:geologic and geophysical maps are published in ten folios, each covering one quadrangle (see index map). The Bopolu quadrangle was systematically mapped by the author in late 1970. Field data provided by private companies and other members of the LGS-USGS project were used in map compilation, and are hereby acknowledged. Limited gravity data (Behrendt and Wotorson, in press ), and total-intensity aeromagnetic and total-count gamma radiation surveys (Behrendt and Wotorson, 1974, a and b) were also used in compilation, as were other unpublished geophysical data (near-surface, regional magnetic component, and geologic correlations based on aeromagnetic and radiometric characteristics) furnished by Behrendt and Wotorson.
