The study of the geology of Nigeria has grown out of the work of the Mineral Survey organized by the Imperial Institute of London in the early 1900's. The Geological Survey of Nigeria, founded some 35 years ago, was faced with the difficult task of mapping the country as a whole and at the same time of investigating the mineral occurrences discovered by the original survey. While extensive areas have now been mapped a vast amount of work remains to be done.
Much has been and is being written on the geology of Nigeria.1 About two-thirds of the country is composed of igneous rocks of great age (known as rocks of the Basement Complex of the Pre-Cambrian age). Most of the mineral occurrences of any present or potential economic importance are associated with sedimentary rocks which wrap around these older rocks to the north, east and south. The alluvial tin deposits of the Plateau are associated with granites and are found in formations consisting of clays and sands which are, in some extensive areas, hidden by a hard capping of volcanic rock (basalt).
The sedimentary formations in the southern part of the country, many thousands of feet in depth, are thought to be potential sources of mineral oils and are now being actively explored.
Nigeria's mining output in 1952-53 accounted for about 1.5% of its gross national product; minerals contributed on the average about 9% of the country's export receipts between 1949 and 1953.____________________