Only 20% of the Sahara is covered with sand!
When you think the Sahara, you probably think of endless sand dunes with the occasional oasis thrown in. However, that is not close to the truth. In reality, only about 20% of the Sahara is covered with shifting sand dunes.
The desert, which covers 8.5 million sq km is formed not just of sand dunes, but also of bare gravel plains, stony plains, mountains and salt covered plains. In the driest parts of the Sahara, the annual rainfall doesn’t exceed 25mm. In places where it does rain, the water evaporates rather than soaking into the ground.