In the basin of the Lower Amazon the Carboniferous beds lie within the Devonian synclinal and crop out on both sides of the river next to the Devonian bands.
A group of highly inclined quartzites, altered conglomerates and jasperoid rocks which crop out on the Umhlatuzi river, between Melmoth and Nkandhla and on the White Umfolosi river above Ulundi Ph ins, is considered by Anderson to represent some portion of the Lover Witwatersrand series.
Where the hard rock does crop out on the surface, it is so excessively weathered as to be with difficulty recognized as rock at all.
They form the backbone of the island, and crop out on the surface at intervals along the mountain chain which runs parallel to the west coast.
Crystalline rocks crop out at several capes; Cretaceous limestones, containing an abundant and specific fauna of gigantic ammonites, occur at Dui on the west coast, and Tertiary conglomerates, sandstones, marls and clays, folded by subsequent upheavals, in many parts of the island.
