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Compared to other major continents, the African Continent has relatively a simple
geological formation, except few regions within the northern and southern sections.
The continent is basically a huge continental shield comprising of the basement
system complex rocks, ranging from pre-Cambrian period (about 450 million years old).
Actually Africa seems similar to other small-sized continental shield zones such
as:-
(a) Baltic shield
(b) Laurantian shield
(c) Brazilian shield and others.
Africa has undergone several mountain building periods known as periods of
orogenesis, which were warped, folded and faulted.
It has been observed that some parts of Africa were folded about 1500 million
years ago which were less disturbed by tectonic activity.
Such parts are stable regions known as crotons.
Some regions were even folded more recently (about 1200 million years ago).
These regions are known as orogens or regions of orogenesis.
The crotons are regions of most gold zones of Africa, diamonds, chromite, asbestors,
iron, etc.
According to Read, H.H. and Janet Watson (1978), the orogen zones are regions
where minerals such as Coper, Lead, Zinc and tin are usually formed. The oldest pre-
cambrian rocks do underlie the continental base which are exposed on nearly 1/3 of
Africa’s surface.
Very little evidence of Africa’s geological history belonging to pre-cambrian era
which was followed by Palaeozoic period (i.e. late Cambrian period, ordovian and
Silurian times) was known.
This is because of the extensive erosional processes which swept away numerous
geological remnants or fossils on the Africa’s surfaces. Although some Cambrian shales,
sandstones and limestones do exist in the Sahara desert region at the moment.
For example in Southern African sections the main rock series after pre-cambrian
seems to be of Devonian age which include folded shales and sandstones around Cape
Range Region. Some parts to the eastern, northern Coasts of Africa, the Crystalline
Complexes sink in many places beneath Mesozoic and Cainozoic sediments. In most
cases Cainozoic are those of Tertiary sediments which were deposited in Marginal
Marine Basins.
The extreme north-west, a part of Alpide folded-belt builds the Atlas Mountains.
Southern end of Africa is occupied by the Cape folded-belt of Palaeozoic period in a belt
zone form.
Titany answered the question on January 12, 2022 at 07:19