By Sid Perkins
In remote regions of the Arctic, Antarctica, and the Australian outback, an explorer can trek across bleak, uninhabited landscapes only to suddenly stumble upon ground decorated with weird patterns. These lonely sites feature ankle-high and meter-wide donuts of gravel; mazes, stripes, and polygonal networks of pebbles, sand, or ice; and sometimes ice crevasses in perfect geometric patterns. The enigmatic configurations, seemingly created without human influence, call to mind the mysterious phenomenon of crop circles, except that the puzzling structures are made of rocks or ice instead of trampled corn or wheat.
Scientists studying so-called patterned grounds have developed geological models for how some of these varied landforms have arisen from the influence of only soil, water, and sunlight. Although such simulations do a good job of reproducing Earth’s variety of patterned ground, one of them may also go much farther: It could explain the hundreds of patterned regions that spacecraft have spied on the surface of Mars.