links & resources
Land and Permafrost
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Many thanks to Jerry Brown for text, images, and enthusiasm.
Further permafrost resources can be found at the end of this page.
The following text and selected figures are based mainly on excerpts from a chapter entitled Permafrost and Periglacial Environments by J. Alan Heginbottom (Canada), Jerry Brown (USA), Ole Humlum (Norway) and Harald Svensson (Denmark). It is scheduled for publication later in 2008 in the U.S. Geological Survey Professional Paper 1386-A edited by Richard S. Williams, Jr. and Jane G. Ferrigno.
Definitions and Distribution
Permafrost constitutes one of the major components of the perennial cryosphere, complementing ice sheets, ice caps, and other glaciers on land; snow patches; and sea ice and ice shelves of the polar oceans. Unlike ice and snow covers that are easily observed by the human eye and on satellite imagery, permafrost terrains are not as easily detected from their surface characteristics. Indirect indicators of present-day and ancient permafrost include surface features such as sorted and non-sorted patterned ground, pingos, ice-wedge polygons, and thermokarst features; such features range in size from small, pitted terrain to large deep lakes. Ice wedge polygons, pingos, and rock glaciers are indicators of an underlying, perennially frozen substrate.
Permafrost or perennially frozen ground is earth material that remains frozen (at or below 0