There is a mysterious and beautiful volcanic ash dune of Shifting Sands situated near Olduvai Gorge. These crescent-shaped mounds are a remarkable phenomenon. Technically they are known as barkan, and they are created when there is sufficient dust on the ground and a unidirectional wind to blow it.

The dust collects around a stone, and continues to accumulate until it literally forms a small dune. The process continues and the dune moves. In this case, the Shifting Sands move around 10 meters every year. The crescents have their two sharp arms pointing the way the wind is going, and the whole shape is beautifully symmetrical. The local Maasai believe the shifting sands originated from their most holy of places – Ol Doinyo Lengai or “Mountain of God”, which you can just see from Olduvai on a clear day.