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January 1, 1993

In 1577, on his second voyage to the New World in search of the Northwest Passage, Sir Martin Frobisher reported finding ground in the far north that was frozen to depths of "four or five fathoms, even in summer," and that the frozen condition "so combineth the stones together that scarcely instruments with great force can unknit them." This permanently frozen ground, now termed permafrost, underlies perhaps a fifth of the Earth's land surface. It occurs in Antarctica but is most extensive in the Northern Hemisphere. In the lands surrounding the Arctic Ocean, its maximum thickness has been reported in thousands of feet as much as 5,000 feet in Siberia and 2,000 feet in northern Alaska.

Publication Year 1993
Title Permafrost
DOI 10.3133/70039262
Authors Louis L. Ray
Publication Type Report
Publication Subtype USGS Unnumbered Series
Series Title General Information Product
Index ID 70039262
Record Source USGS Publications Warehouse