Chad Basin S.W.-Bouguer gravity contours : Geological Survey of Nigeria 1:500,000 /
Great Britain.Directorate of Overseas Surveys.
Cratchley, C. R.
[Tolworth, Surrey] : The Directorate,
1963.
"Gravity information compiled from measurements and computations carried out during 1960-61 by C.R. Cratchley ..."
Relief shown by spot heights.
Includes magnetic variation diagrams, grid belt designation, and reliability diagram.
Gravity