There’s an odd phenomenon in southern Africa – especially in Namibia – that the locals call “fairy circles”, whereby vegetation refuses to grow inside a circle of anywhere from 3 to 10 meters in diameter. Even stranger, the circles are dynamic – apparently they grow and “die”, to be filled in by grasses. While they are active, seedlings will sometimes take root inside the circle, but they eventually wither and die.
Here are a photo and a video so you can see what I’m talking about. The video should start 6:40 in, where the fairy circles show up. If it doesn’t, fast forward.
Up until now, there has been no scientific explanation for the phenomenon. At least three hypotheses have been suggested (in the early 1970s), but all have been disproven thus far (by South African scientist Gretel van Rooyen):
- The soil is (for some reason) radioactive. This was disproven by simply sending in the soil for testing.
- The soil is toxic due to residue left behind by the milkbush plant – Euphorbia damarana. This was proven by successfully growing plants in soil taken from areas where milkbush plants are growing. They grew without any trouble.
- The third option was termites. People thought termites might simply be keeping the area clean of all plant debris, preventing growth. So van Rooyen dug up some areas down to 2 meters, and found no termites – another theory debunked.
However, her experiments strongly suggested something was toxic in the soil. But what, and how did it get there?
And now for the latest. Apparently University of Pretoria researcher Yvette Naude, working with van Rooyen found traces of substances that suggest the culprit may be gases (hydrocarbons) seeping up from the ground underneath. It seems there are gases seeping up and not only displacing the oxygen in the ground, but also changing the chemistry of the soil in such a way that plants cannot grow there. At least temporarily. It’s all detailed in a Journal of Arid Environments article. If you happen to speak Afrikaans, today’s Die Republikein. Mystery solved! Or is it?
Regardless, the researcher did caution that this doesn’t mean we should all start drilling for oil under the Namib desert.