A Dune, Dunes, a Desert: all about the formation of dunes

How do dunes form?

To form a dune and, even more so, a dune desert, a number of conditions must be met. A large quantity of sand, at least partly dry, must be available in a region bathed by frequent and fairly strong winds. Pushed by the winds, the grains of sand move in successive leaps before settling in a place where the force of the wind has become too weak. The grains accumulate to form a dune.

This feature often makes it possible to identify the direction of the prevailing winds. The side of the dune with a gentle slope is facing the wind, while the side with a steeper slope is facing away from it.

The different configurations of Saharan dunes

The variety of weather conditions influences the shape of the dunes. Depending on the strength of the winds, the dune massifs adopt different configurations, such as half-moon dunes, linear dunes, star dunes, dome dunes or parabola dunes.

The most common configuration in the desert is the half-moon or transverse dune. It is formed by winds blowing constantly in a single direction.

Linear dunes are generally made up of long straight or winding ridges. Often extending over several kilometres and rarely isolated, this type of dune is formed in places where winds blow in two directions.

Star dunes have a pyramid shape formed by multi-directional winds and are common, particularly to the east of the Sahara.

Dome dunes are oval or circular in shape and are among the rarest to be seen.

Formed by one-way winds, parabola dunes are generally found in coastal deserts. They are U-shaped and often form when vegetation begins to grow at the ends of a sand formation, stopping the natural progression and giving the dune its U-shaped appearance.

Use these tips to help you recognise the shape of the dunes on your next trip to the Moroccan desert.