Mann's essay, "On Patterned Ground," is a commentary on an article in the same issue of "Science" submitted by Mark Kessler and Brad Werner of the University of California-San Diego. Their article, "Self-Organization of Sorted Patterned Ground," is based on a computer model that simulates the interaction of three different physical processes operating within a field of cyberspace tundra to create sorted polygons and stripes. The three critical processes identified by Kessler and Werner are frost heaving, the upward squeezing of domains of stones heaved out of the soil and the gravitational sorting of stones piled up by heaving.
Together, these simple processes, acting over centuries of simulated time, create intricate, three-dimensional patterns on the ground resembling what you see in Alaskan mountain ranges and on the North Slope.
Mann was invited to comment on the Kessler-Werner article because of his expertise in polar soils, which extends back to the late 1970s when he studied soil development in Spitsbergen, an arctic archipelago north of Norway. Since then Mann has worked on several projects involving patterned ground in northern Alaska, Antarctica and in mountain ranges in the western U.S. Mann's interest in patterned ground derives from the fact that it is an example of self-organization, the process by which nonliving things assume order and pattern without the intervention of either a creator or natural selection.
"There is nothing in the physics of a shovelful of stony mud that can predict the emergence of an intricate pattern of interlaced, stone-bordered polygons covering many square meters," said Mann. "Self-organization represents a creative force whose existence we barely suspected just a decade ago."
Mann is working with Brad Werner on a related project dealing with the self-organization of the Alaskan landscape. Werner is currently on sabbatical and studying at UAF's Geophysical Institute.
Note to Editors: View available photos at ftp://www.uaf.edu/pub/univrel/releasephotos/PatternedGround/
CONTACT: Carla Browning, UAF University Relations at (907) 474-7778 or carla.browning@uaf.edu for high resolution photos.
Photo cover copyright © Science: Raised rings of stones surrounding circular fine-grained domains (circle in foreground, diameter ~2 m) on Kvadehuksletta, western Spitsbergen. These features are only a small subset of the diverse patterns of stones and soil-including labyrinths, stone islands, sorted stripes, and sorted polygon networks-that self-organize in periglacial regions, as discussed on page 380. [Photo: M. A. Kessler]
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