Why is the Sahara desert so flat?

The Sahara Desert is predominantly flat due to a combination of geological processes and erosion over millions of years. Its vast expanse of sand dunes and gravel plains has been shaped by wind erosion, which has scoured the landscape, removing softer materials and leaving behind harder substrates. Additionally, tectonic activity has contributed to the formation of flat basins, while climatic conditions have limited vegetation growth, preventing the development of more varied topography. These factors together create the expansive, flat terrain characteristic of the Sahara.