Fairy circles appearing in the Australian outback are causing controversy and discussion around the world, as scientists and laypersons alike ponder their mysterious origin. The phenomenon has been seen previously in southern Africa, but this marks their first-known appearance anywhere else in the world.
The fairy circles are found near the town of Newman, and were discovered in aerial photographs. The bare patches within fields of vegetation form in the shape of a hexagon, each stretching from 13 to 23 feet across. The hardened soil in their beds prevents the growth of any vegetation.
Geologists have three main theories to explain the formation of the mysterious phenomenon. One possibility is that carbon dioxide gas seeps up through the ground, killing vegetation. Another idea is that insects, such as ants or termites, may be feeding on the roots of the vegetation, creating the barren regions. Still, others hold that the unusual features are the result of plants organizing themselves in such a way as to maximize the availability of water.
"The interesting thing about fairy circles is that they are spread with great regularity and homogeneity, even over vast areas, but they occur only within a narrow rainfall belt," said Stephan Getzin of the Helmholtz Centre for Environmental Research (UFZ).
Some researchers are dubious of this idea, questioning why plants in other dry areas of the world do not exhibit similar patterns. Although plants elsewhere do form unusual patterns in the quest for moisture, it is only in southern Africa, and now Australia, where barren regions form in hexagons.
Getzin and Israeli researcher Hezi Yizhaq traveled to Australia in order to investigate the fairy circles found down under. The team measured temperatures in the circles and compared measurements with nearby areas, and they also took soil samples and recorded water flow.
Fairy circles found in Australia were found to be highly-similar to features found on the African continent.
The team believes that self-organization of the grasses, driven by the quest for water, is responsible for the odd formations. When the soil is exposed to sunlight, researchers note, it bakes to a hard surface that cannot be permeated by plants.
The theory that termites and ants are responsible for the features was refuted by the recent studies, as Australia is not home to any insects capable of carrying out such damage.
Investigators will now search for other areas where similar fairy circles may be found.
Analysis of the Australian fairy circles was profiled in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).