Mauritania a country in northwest Africa is bordered by the North Atlantic Ocean on the west, by Senegal to the southwest, by Mali on the east and southeast, by Algeria on the northeast and by the Morocco-controlled Western Sahara on the northwest. It covers a total area of 1,030,700 km² and is comparable in size to Egypt. Mauritania is generally flat, forming the vast, arid plains of the Sahara. These are broken by occasional ridges, isolated peaks and southwest-facing scarps in the centre of the country that separate a series of plateaus, the highest of which is the Adrar Plateau reaching an elevation of 500 metres. The concentric Guelb er Richat Structure is a prominent feature of the north-central region. The largest of the hills that rise above the plateaus is Kediet Ijill at 915 m. About three quarters of Mauritania is desert or semidesert. The plateaus of the Taoudeni Basin descend toward the northeast to the barren El Djouf, or "Empty Quarter," a vast region of large sand dunes. Mauritania has four ecological zones: the Saharan Zone, the Sahelian Zone, the Senegal River Valley, and the Coastal Zone. The Saharan Zone makes up the northern two-thirds of the country. The savannah-like Sahelian zone is a relatively narrow belt bordering the Senegal River Valley. The Senegal River defines the border with Senegal and the valley supplies most of the country's agricultural production. The coastal zone includes Dakhlet Nouadhibou, one of the largest natural harbours on the west coast of Africa with the Mauritanian port and railhead of Nouadhibou located on the eastern shore.


The geology of Mauritania can be subdivided into four major domains: The Archean Reguibat Shield in the north of the country which strikes into Western Sahara (southern Morocco) and Algeria, comprising gneiss, amphibolites and marble; the Neoproterozoic N-S striking Mauritanide belt, comprising dominantly sediments folded and thrust during the Variscan orogeny; the Taoudeni Basin of predominantly fine-grained clastic sediments of Neoproterozoic to Phanerozoic age, covering most of central and southern Mauritania; and parts of the Senegal basin in the southwest of the country with marine sediments of Jurassic to Recent age. Sand dunes cover about 50% of Mauritania’s surface, which forms a vast peneplain studded with inselbergs on the folded belts.