Under the Atlantic, a pair of convection currents has moved the continents to the East and West. The details of that pair of currents have been analyzed here, but for public introduction, first a simplified section along equator is presented:
The seafloor has some 3D effect, just to remind us that when we draw sections of geological features, it is to help us understanding the whole picture.
As pointed out on the drawing, upwelling takes place in the middle. Also, the distance between the continents at equator is exactly 60°, and a convection cell section spans exactly 30° from east to west.