Beginning in the south-east corner of the Gold Coast colony this range, composed of quartzites and schists, extends beyond the borders of Togoland into upper Dahomey.
The dark bituminous layers of clay slate, which occur intercalated among the quartzites, have led, here as elsewhere, to the hope of coming upon a seam of coal, but it is contrary to experience that coal of any value should be found in rocks of that age.
Many of the block mountains of the Great Basin are of complicated internal structure, showing rocks of all ages - slate, limestone, quartzites, granite, multi-coloured volcanic rocks, and large areas of lava overflow.
The metamorphic rocks of the rest of Mainland are principally coarse gneisses, micaceous and chloritic schists, quartzites, &c.; in these rocks at Tingwall and Wiesdale considerable beds of limestone occur, which may be followed across the island in a northerly direction to Yell Sound, and to Dales Voe in Delting.
Quartzites, Conglomerates and Shales of Nkandhla, Umfolosi river.