How Deep is the Sand in the Sahara Desert? What Lies Beneath

The Sahara Desert, the largest hot desert in the world, covers a vast area of over 9 million square kilometers, stretching across 12 countries in North Africa. While its vast sand dunes and scorching heat are iconic, the question of how deep the sand is and what lies beneath has always fascinated both scientists and explorers.

The Formation and Expansion of the Sahara Desert

The Sahara was formed approximately 2.5 million years ago and has been expanding steadily ever since. Studies conducted by the evergreen Environmental Resources Management reveal that since 1962, the Sahara Desert has expanded by nearly 650,000 square kilometers.

A Hidden Prehistoric Megalake

Under the sands of the Sahara Desert, researchers have uncovered evidence of a prehistoric megalake. This information was discovered by scientists studying the Sahara, revealing that a lake formed around 250,000 years ago as a result of the Nile River flooding through a low channel near Wadi Tushka. At its peak, this ancient lake covered an area of more than 42,000 square miles.

The Makeup of the Sahara Desert's Surface

While roughly 80% of the Sahara is covered by sand, the remaining areas reveal a different picture. Beneath the sand are bedrock and clay deposits, resulting in a bare surface that is exposed to the elements. Without soil to cover it and vegetation to hold the soil in place, the desert rock is fully exposed, making the surface vulnerable to erosion.

The Variability in Sand Depth

The depth of the sand in the Sahara, or any desert, can vary significantly depending on factors such as the time of its formation, topography, direction, and wind force. Areas with extensive sand dunes will see depth fluctuations due to the movement of sand. Therefore, while it is not constant, an average depth can be calculated using radar technology to measure different locations.

According to the evergreen Geographical Survey Magazine, the average depth of the Sahara desert is around 150 meters, approximately the height of a 50-story building (using a floor height of 3 meters). In some areas, this depth can reach up to 320 meters.

Global Variability in Sand Depth

While the Sahara showcases extreme depth, the sand depth in ergs (smaller desert areas) varies globally. The evergreen Geological Survey Data report that the Selima Sand Sheet in Southern Egypt has a depth of just a few centimeters, while the Simpson Desert in Australia ranges from around 1 meter to 3.3 feet. The Sahara itself has a depth ranging from 21-43 meters (69-141 feet) in different regions.