The Amazon is aligned from west to east, and the estuary is on the equator line. According to the convection rolls model, the estuary is exactly on the down-welling division line between large convection rolls of lower mantle. From there, 30° westwards, is the west coast of S-America with a deep trench. The trench is connected with a down-welling division line of the upper-most convection rolls.
The Amazon River actually follows the equatorial parallel. The 30° span is then followed by 60° span along equator to Africa, and the 30° span from west coast of Africa to the Great Rift Valley. At each of these points, a division line of convection rolls of lower mantle is found. The Amazon is roughly marked with a blue line.