Topographic Regions

Topographic Regions

The broad, mostly level valleys of the Niger and Benue rivers form Nigeria's largest physical region. The Niger enters the country from the northwest, the Benue from the northeast; they join at the city of Lokoja in the south central region and continue south, where they empty into the Atlantic at the Niger Delta. Together, they form the shape of a Y. Population densities and agricultural development are generally lower in the Niger and Benue valleys than in other areas. North of the Niger Valley are the high plains of Hausaland, an area of relatively level topography averaging about 800 m (about 2,500 ft) above sea level, with isolated granite outcroppings. The Jos Plateau, located close to Nigeria's geographic center, rises steeply above the surrounding plains to an average elevation of about 1,300 m (about 4,200 ft). To the northeast, the plains of Hausaland grade into the basin of Lake Chad; the area is characterized by somewhat lower elevations, level terrain, and sandy soils. To the northwest, the high plains descend into the Sokoto lowland.

Southwest of the Niger Valley (on the left side of the Y) lies the comparatively rugged terrain of the Yoruba highlands. Between the highlands and the ocean runs a coastal plain averaging 80 km (50 mi) in width from the border of Benin to the Niger Delta. The delta, which lies at the base of the Y and separates the southwestern coast from the southeastern coast, is 36,000 sq km (14,000 sq mi) of low-lying, swampy terrain and multiple channels through which the waters of the great river empty into the ocean. Several of the delta's channels and some of the inshore lagoons can be navigated.

Southeastern coastal Nigeria (to the right of the Y) consists of low sedimentary plains that are essentially an extension of the southwestern coastal plains. In all, the Atlantic coastline extends for 850 km (530 mi). It is marked by a series of sandbars, backed by lagoons of brackish water that support the growth of mangroves. Large parts of Africa's Bight of Benin and Bight of Biafra fall along the coast. Because of the Guinea Current, which transports and deposits large amounts of sand, the coastline is quite straight and has few good natural harbors. The harbors that do exist must be constantly dredged to remove deposited sand.

Inland from the southeastern coast are progressively higher regions. In some areas, such as the Udi Hills northwest of Enugu, escarpments have been formed by dipping rock strata. Farther east, along Nigeria's border with Cameroon, lie the eastern highlands, made of several distinct ranges and plateaus, including the Mandara Mountains, the Shebeshi Mountains, the Alantika Mountains, and the Mambila Mountains. In the Shebeshi is Dimlang (Vogel Peak), which at 2,042 m (6,699 ft) is Nigeria's highest point.