The Republic of the Congo, also known as "Congo-Brazzaville", is an equatorial country in the central-western part of sub-Saharan Africa. It has a short Atlantic coast and is bordered by Gabon to the west, by the Democratic Republic of the Congo to the south and east, by Cameroon and the Central African Republic to the north, and the Angolan enclave of Cabinda to the south. The Congo covers a total area of 342,000 km² of which 500 km² is water. About 57 percent of the country is covered by rain forest. The terrain comprises a coastal plain in the southwest, a southern basin, a central plateau and a northern basin. The highest point, at 1,020 m, is Mont Nabeba in the Mayumbe mountains. The major rivers are the Congo River at the border with the Democratic Republic of the Congo, and the Kouilou-Niari River. The 169 km-long Atlantic coast has several important ports.  About 70% of Congo-Brazzaville's 4.86m population (January 2016 estimate) population lives either in the capital Brazzaville or the main port of Pointe-Noire, or along the rail link between them. 


The Republic of Congo is underlain in the northwest and southern parts by rocks of Archean to Neoproterozoic age, dominated by granitic/granitoid units hosting remnants of schist, greenstones and banded iron-formation. The eastern part is covered by Quaternary alluvial sediments of the Congo Basin. The coastal basin is made up of Cretaceous to Recent marine sediments that are fault – bounded to Precambrian rocks of the Proterozoic Mayombe Supergroup.