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Science 17 November 2006:
Vol. 314. no. 5802, p. 1045
DOI: 10.1126/science.314.5802.1045d
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This Week in Science

The shattering of rock by ice freeze has long been thought to be caused by volumetric expansion when water distributed within the rock freezes. However, Murton et al. (p. 1127; see the Perspective by Hallet) demonstrate experimentally an alternative mechanism, called ice segregation, which operates when there is a temperature gradient. As the freezing front moves through the rock, it squeezes water from its pores into pockets where ice lenses form, which causes the rock to crack. Cold-room experiments quantified this process by monitoring heave, temperature, moisture, and pore-pressure for two distinct thermal regimes. The results are verified with numerical modeling and are consistent with field observations. In warming climates, such fracturing may increasingly destabilize permafrost in polar regions.




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Science. ISSN 0036-8075 (print), 1095-9203 (online)