The San people of Namibia believed these rings were bubbles blown by a dragon under the Earth. For years, scientists struggled to identify the cause of phenomenon, with theories ranging from poisonous bushes, carbon dioxide leakage and ant or termite activity. But, sadly, such fanciful origins have now been ruled out.
The circles, ranging from two to 15 metres in diameter - shown here in the Namib-Naukluft National Park in Namibia - emerge from the behaviour of grasses in very dry regions. "It's a self-organising mechanism," says Stephan Getzin from the Helmholtz Centre for Environmental Research in Germany, who has co-authored a "fairy circles" study.
Grasses suck up water and nutrients, killing vegetation to leave spots with a hard crust. "When it rains, the circles are a source of water," says Getzin. "After rainfall, the circles disappear."
Getzin and his researchers used fieldwork, remote sensing, spatial-pattern analysis and mathematical modelling to map the grass patterns in Namibia and the western Australian outback, where a 20km2 area of fairy circles was recently observed. "From two different ecosystems, the same instability creates a similar pattern," explains Ehud Meron, from Ben-Gurion University of the Negev, Israel, who did the modelling. But the fairy circles still hold some secrets - for now. "We plan to use drone imagery to understand how the plants arrange themselves," says Getzin.
This article was originally published by WIRED UK
