No geologist ventures to pontificate on this subject, but it seems feasible that it is the Sahara . Located in North Africa, it is the largest non-polar desert in the world, stretching across thirteen countries. It occupies between 8.6 and 9 million km2 , a surface very similar to that of the United States. This disproportionate figure is not reached anywhere near by other sterile regions of the Earth, such as the Saudi Arabian desert, with 2.5 million km2, and the Gobi, which is around 1.2 million km2.
The popular image we have of a desert is an immense space covered by a kilometer-long layer of sand that, incidentally, is formed by the wind erosion of the rocks. However, the reality is very different. 70% of the Sahara is made up of pure gravel and rock, so the sandy deposits only constitute a third of its entire extension. As a curious fact, we can highlight that the wind sometimes sweeps gigantic desert extensions, exposing a stony and cobbled bottom that receives the name of serir or reg. This is how the loes of China have been formed, carpets of sand from the deserts of Central Asia with more than 600,000 km2 in extension and 100 meters deep.
