The Seychelles Islands are the highest points of the Mascarene Ridge, an Indian Ocean ridge running in a generally north-south direction. The granitic islands rise above the sea surface to form a peak or ridge which, in the case of Mahé, attains an elevation of 912 m (2,992 ft) at Morne Seychellois, the highest point. Rugged crests, towering cliffs, boulders, and domes contribute to the islands' great natural beauty. Here and there, in the hollows in the rock relief, are pockets of lateritic soil, often very thin and easily eroded. Mahé possesses white, sandy beaches behind which are flats of coral and shell known locally as plateaus. Small streams descending the mountain slopes deposit alluvial material, creating the most fertile soils on the island.
The coralline Seychelles are, in contrast, low lying, rising only a few feet above the surface of the sea. Many have the typical Indian Ocean lagoon. Soils tend to be thin, with poor moisture retention. These islands are suited only to the coconut palm and a few other species.