Cleared circles or patterns found on the ground surface, even in areas with rocks, can be formed by several natural phenomena rather than being created by human activity.
The possibility that some of these cleared circles are natural rather than cultural phenomena has been raised (cf. McAuliffe and McDonald 2006). These natural processes can create circular or patterned areas on the ground surface, which might occur near or interspersed with rocks.
Here are some possible natural sources identified in the reference:
- Animal Burrowing: Animals digging burrows can disturb and clear vegetation or loose material in a circular or patterned area around the entrance or within their burrow system.
- Growth of Bushes: The dense growth of a single bush or clump of vegetation can sometimes clear the ground around its base, creating a circular pattern as it grows and spreads.
- Sweeping of Areas by Wind-Blown Bush Branches: In windy environments, branches of bushes can repeatedly sweep the ground surface around the plant, clearing away soil, dust, and small debris in a circular area over time.
- Soil Action: Natural processes within the soil itself, such as freeze-thaw cycles, shrink-swell clays, or differential erosion, can sometimes lead to the formation of patterned ground, which may include circular features.
These natural actions can lead to the appearance of cleared circular areas on the ground surface, including in rocky or semi-rocky environments, potentially leading to misidentification as human-made features.
