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No. 88: Jul-Aug 1993

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Self-organized stone stripes

"Geometrically regular stripes of stones are found on many unvegetated alpine and polar hillslopes; known as 'sorted stripes' because of the characteristic textural sorting between surface stones and fine-grained soil, they contrast markedly with the lack of order typical of natural landscapes. The spacing of the stripes can range from centimeters to meters (about 10-20 times the average stone diameter), with individual stripes extending downslope for many tens of meters. A variety of formative mechanisms have been proposed, but it is still unclear how such orderly stripes can arise spontaneously, and what dictates the spacing."

B.T. Werner and B. Hallet, authors of the foregoing partial abstract, have mathematically simulated the displacement of surface stones under the forces generated by the growth of needle ice in the underlying soil. As the number of freeze-thaw cycles increases into the thousands, computer simulations show the surface stones gradually arraying themselves into linear patterns.

(Werner, B.T., and Hallet, B.; "Numerical Simulation of Self-Organized Stone Stripes," Nature, 361:142, 1993.)

Reference. These stone stripes represent just one type of "patterned ground." Other examples may be found in ETP1 in our catalog: Carolina Bays, Mima Mounds, described here.

From Science Frontiers #88, JUL-AUG 1993. 1993-2000 William R. Corliss