Crystal Mountains in Gabon

Adjacent to the western part of the northeastern plateau, the Monts de Cristal are a geological unit made up of very ancient crystalline rocks.

The relief is cut by deep, often straight valleys.

Its western edge has a very rugged topography, due to rejuvenation that has carved out, on orthogonal fault lines, a complex system of steep ranges and incised valleys, drained by torrential rivers cut by frequent waterfalls (Kinguélé Falls, 95 m high, and Tchimbélé Falls).