Circles in the sand

A dragon stirs deep under a desert. It breathes a poisonous gas as it goes. The gas bubbles up to the surface. There, it burns circles of bare dirt in the grass.

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

Thousands of circles stretch as far as the eye can see. Some are small. Others are wide. The dragon has been busy.

for a Cause

Scientists don’t believe in dragons. They believe something else causes these strange circles. Some think ants chew on the roots of the grasses. Others think a toxic plant may spread its poison and kill the grasses.

These ideas are only theories. They could be possible. Yet scientists have to prove a theory. Only then will a theory become a 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.



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

Desert Discoveries

Norbert Juergens wants to solve this mystery. He’s a biologist. He studied 1,200 of the circles.

Juergens looked for things all the circles had in common. He tested the dirt and measured water in the soil. He made a list of animals and plants in the circles. He charted the weather. Then he studied his data.

Common Clues

Juergens found something surprising. In dry weather, the grasses around the circles stayed alive. He wondered why. Then he found wet sand under each circle. The water in the sand kept the grass alive.

He also found sand termites under each circle. Water and termites were the common clues. Juergens thought about them and formed a theory.

sand termites

Mystery Solved?

Juergens thinks that termites eat the grass roots. That kills the grass and leaves a circle of bare dirt.

When rainwater soaks into the dirt, it forms a pool of water under each circle. The termites drink this water. That’s how they survive. Grass around the circle soaks up the water. That’s why the grass stays alive. Maybe now the mystery is solved!

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