South Cameroon Plateau - Geology

Geology

Metamorphic rocks such as gneiss, mica, migmatites, and schists make up the South Cameroon Plateau's basement. Deposits of these rocks appear along fault lines south of Yaoundé, where schists and quartzites are found; near the Dja River, where limestone and schists occur; and along the Ntem River, where gneiss, granite, mica, migmatite, and schists occur. The plateau's western portions are made up primarily of gneiss. These rocks are millions of years old.

The plateau's soils are predominately ferrallitic and lateritic, the result of decomposing crystalline and sedimentary stone. The soil colour varies from red or reddish brown in the interior to yellow along the coast, where greater humidity causes a colour change. The soil is made up of decomposing crystalline rocks (granite, gneiss, schists, and michachists), or sedimentary rocks in the coastal area. Soils are deep, averaging 10 m., although they are thinner in the north, where rainy seasons are shorter. Ferrous deposits in the soil are quite hard and are used to make bricks. Constant leaching of silica by percolating water prevents the soils from being very productive without fertilisation.