Nature's repeating patterns are part of the beauty and wonder of our world. A team from around the world, including one researcher from Washington University, used modern tools and techniques to explain repeated patterns of stones formed in cold landscapes. The new study was published in the Proceedings of the National Academy of Sciences on Oct. 5. It uses experimental tools to demonstrate how needles of ice can grow randomly on frozen ground and gradually move rocks into repeating, regular patterns. These striking features are described by the team, which is based in China and Japan. They use a combination computer modeling and experimental methods to explain them. “The existence of these amazing patterns which develop without any intervention by humans is pretty striking in the natural world,” commented co-author Bernard Hallet. He is a UW professor of Earth and space sciences and a member of the Quaternary Research Center.
Hallet stated that this type of selective growth has interesting feedbacks between the stone size, soil moisture and growth of ice needles. Hallet had reviewed a previous scientific paper by Anyuan Li. This was previously at Shaoxing University, and now at University of Tsukuba in Japan. They began a collaboration that combines Hallet's extensive expertise in studying patterns in nature with Li's background in experimental science, computer modeling, and Li's.
Further experiments were done to determine how the patterns changed according to the amount of stones, slope of ground and height of ice needles. Stone concentration is another factor. The results of these experiments led to the development of a computer model that can predict the appearance of patterns depending on the amount and concentrations the stones are on the frost-prone surfaces.