Geography of Angola - Geology

Geology

The rock formations of Angola are met with in three distinct regions:

1. the littoral zone,
2. the median zone formed by a series of hills more or less parallel with the coast,
3. the central plateau.

The central plateau consists of ancient crystalline rocks with granites overlain by non-fossiliferous sandstones and conglomerates of Paleozoic age. The outcrops are largely hidden under laterite. The median zone is composed largely of crystalline rocks with granites and some Palaeozoic unfossiliferous rocks. The littoral zone contains the only fossiliferous strata. These are of Tertiary and Cretaceous ages, the latter rocks resting on a reddish sandstone of older date. The Cretaceous rocks of the Dombe Grande region (near Benguella) are of Albian age and belong to the Acanthoceras mamillari zone. The beds containing Schloenbachia inflata are referable to the Gault. Rocks of Tertiary age are met with at Dombe Grande, Mossamedes and near Loanda. The sandstones with gypsum, copper and sulfur of Dombe are doubtfully considered to be of Triassic age. Recent eruptive rocks, mainly basalts, form a line of hills almost bare of vegetation between Benguella and Mossamedes. Nepheline basalts and liparites occur at Dombe Grande. The presence of gum copal in considerable quantities in the superficial rocks is characteristic of certain regions.