Geography:

Basikly, the topography of Nigeria consists of plains in the north and south interrupted by hills in the middle of the country. The Sokoto Plains lie in the northwestern corner of the country, while the Borno Plains are in the northeastern corner. Plains, which become waterlogged during the rainy season, are found in the areas nearby. The characteristic landforms are high plains with shallow, broad valleys dotted with numerous hills or isolated mountains, called inselbergs, the underlying rocks are crystalline sandstones appear in river areas, though. 
Neda Peneva 2022