Circles in the sand

A dragon stirs deep beneath a desert. It slithers through the sandy dirt, breathing a fiery, poisonous gas as it moves. The gas bubbles up to the surface. There, it burns circles of bare dirt in the grass.

Or so the story goes. No one has seen this mythical beast. Yet, some people in southern Africa say it’s there. It’s how they explain the mysterious circles that appear on the eastern edge of the Namib Desert.

Thousands of circles stretch as far as the eye can see. Some are small, just one meter (three feet) wide. Others are as wide as 50 meters (164 feet). It would seem that the dragon has been busy.

for a Cause

Not everyone believes in dragons. So, scientists have looked for other causes for the circles.

Some think that, like the mythical dragon’s fiery breath, a gas bubbles up. Others think that ants may chew the roots of the grasses. Still others think that toxic plants may spread their poisons. Any of these actions could have the same effect. They could kill the grasses.

These are all theories, or ideas. They seem possible. Yet, scientists have to prove a theory before it’s accepted as fact.

Mysterious circles stretch as far as the eye can see.

Mysterious circles of bare dirt dot this desert on the west coast of southern Africa.


Namib Desert

Norbert Juergens and his wife, Irmel, collect weather data near a circle.

Desert Discoveries

One scientist thinks he may have solved this mystery. Biologist Norbert Juergens has visited this desert 40 times. He’s studied 1,200 circles, looking for evidence of what caused them. He’s looked for patterns among the circles, trying to discover what they have in common.

The biologist sifted through the dirt inside the circles. He tested the dirt for chemicals and measured how much water was in it. He recorded the animals he saw in the circles. He wrote down the names of plants growing nearby. He tracked changes in
the weather.

Then Juergens studied all his data. He found some differences between the circles. Colonies of ants crawl through some. Spiders spin webs in the grasses growing around others. Aardvarks even visit some circles.

Common Clues

Juergens didn’t just find differences among the circles. He also found similarities.

Each circle had dry, sandy soil in its center. He also found something surprising. Even in the dry season when it barely rains, the grasses around the circles stayed alive. To find out why, he dug deep into the soil. He discovered wet sand under each circle. The grass roots tapped into the water to keep the grasses alive.

Juergens also found something else in every circle. He found sand termites. These termites tunnel through dirt. They chew on plant roots.

Juergens studied these common clues. He looked for ways they could connect. Then he came up with his own theory.

sand termites

Mystery Solved?

Juergens thinks that termites eat some grass roots. That kills the grass growing above the roots and forms a circle of
bare dirt.

When it rains, water soaks into the dirt. It’s saved in a pool under the dirt. The termites drink this water. The grasses around the circle soak it up. It’s how these insects and plants survive in the desert during the dry season.

Juergens will have to study more circles to prove if his theory is correct. Yet, he may be one step closer to solving the mystery of the circles in the sand. The termites aren’t fire-breathing dragons. Still, they’re pretty remarkable. These tiny insects may have created one of nature’s strangest mysteries.

A view from above shows circular patches dotting the land in the Namib Desert.