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Louis L. Ray

Publications and source records attributed to Louis L. Ray.

4 recordsLinked to original sources
USGS1993

Permafrost

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.

General Information Product↗
USGS1992

The Great Ice Age

The Great Ice Age, a recent chapter in the Earth's history, was a period of recurring widespread glaciations. During the Pleistocene Epoch of the geologic time scale, which began about a million or more years ago, mountain glaciers formed on all continents, the icecaps of Antarctica and Greenland were more extensive and thicker than today, and vast glaciers, in places as much as several thousand feet thick, spread across northern North America and Eurasia. So extensive were these glaciers that almost a third of the present land surface of the Earth was intermittently covered by ice. Even today remnants of the great glaciers cover almost a tenth of the land, indicating that conditions somewhat similar to those which produced the Great Ice Age are still operating in polar and subpolar climates.

General Interest Publication↗