'Fairy circles' baffle scientists
2004-03-31 13:14
Paris - Attempts by South African botanists to explain "fairy circles" in Namibia - bizarre outlines in the grass, somewhat similar to Britain's bogus crop circles - have drawn a complete blank, New Scientist reports.
The circles comprise innumerable discs of completely bare sandy soil, ranging from two to 10 metres across, found in grass on Namibia's coastal fringe.
Over the past three decades, scientists have wrangled over how the shapes are formed.
There are three main theories: radioactive soil, which prevents plants from growing; toxic proteins left in the soil by a poisonous plant called the milkbush; and termite colonies that mop all the seeds, leaving nothing left to grow.
Each of these explanations has now been examined at length and then discarded, in a study by South African researchers.
Tests of soil samples taken from "fairy circles" found all to be negative for radioactivity, and desert plants were successfully grown in the lab on soil on which milkbushes had grown.
As for the termites, the team dug trenches up to two metres deep in and around the circles, but found no sign of these insects or their nests, present or past.
Lead scientist Gretel van Rooyen, a botanist at the University of Pretoria, is now exploring the theory that, somehow, toxic elements are deposited in the shape of the circle, making it impossible for plant life to get established there.
"But even if we find them, how they came there is the next problem," New Scientist quotes her as saying in next Saturday's issue.
For the moment, she admits wryly, "we're left with the fairies".
Fairy circles occur in a broken belt in the pro-Namib region, from southern Angola to the Orange River in South Africa and have become so famous that they are included in visitors' tours.
Other explanations for the phenomenon include electromagnetic waves, land mines, radiation, UFOs, meteorites, other-worldly creatures and God.
Britain's rash of crop circles in the 1980s were initially attributed by the superstitious to aliens or divine powers.
It was then discovered the circles were made by pranksters, who carefully flattened down wheat and other crops using sticks and chains. In Namibia's case, though, human intervention has clearly been ruled out.