Permafrost Occurrence in the Front Range, Colorado Rocky Mountains, U.S.A.

Abstract

AbstractIn contrast to the extensive and rapidly growing body of knowledge on permafrost in the Eurasian and North American Arctic and sub-Arctic, little is known about permafrost occurrence in the high mountain regions of the world. Preliminary results of permafrost studies from the Colorado Rocky Mountains are presented.Above tree line (about 3 500 m) in the Front Range, scattered patches of permafrost begin to occur under wet sites blown free of snow in winter with a mean annual air temperature of about — 1.0°C. At greater elevations, with correspondingly lower mean annual air temperatures (extreme case — 9.0°C and 4400 m), permafrost becomes more extensive and probably exceeds 60 m in thickness. These initial results are derived from a skeleton ground-temperature observation program supplemented by indirect evidence and by data gathered from engineering and mining operations in the high country. It is probable that under the higher summits and ridge crests the alpine equivalent of the continuous zone of Arctic permafrost can be anticipated.