Geometrical relationships between the tectonic directions of Precambrian belts in the Central Africa area (redrawn from Choubert, 1935, Plate A). Africa is in its orientation before the Atlantic opening. Note the almost orthogonal structures in the centre of the sketch, which seem to be the result of a belt having been squeezed between two former Precambrian blocks, rather than from a swirl linked to Earth’s rotation. 1- Precambrian belt structural directions. 2 − Belt of unknown age. 3 − Post-Hercynian volcanic rocks (red). D: Devonian; P: Permian; M: Mesozoic.