Nigeria with a total area of 923,800 sq km occupies about 14& of land area in West Africa. The country lies between 4oN and 14oN, and between 3oE and 15oE. It is bordered respectively in the north, east, and west by Niger, the Cameroon, and Benin Republic, while the Gulf of Guinea, an arm of the Atlantic Ocean, forms the southern border. Most of Nigeria is covered with Pre- Cambrian rocks, but there are also metamorphic and sedimentary rocks of Eocene times as well as volcanic rocks. In general, three types of geologic structures exist in Nigeria, namely, areas of uplift, basins of sedimentation, and isolated volcanic areas. The areas of uplift are made up of the oldest rocks in Nigeria - the basement complex rocks.The basins of sedimentation are the down-warped areas, which were drowned by the sea at different times and in which sediments eroded from the areas of uplift were laid down.
