Curtis M. Obi T. D. Hamilton 1982 <p><span>Some 70 pingos occur at 27 separate localities within and near the Brooks Range. The pingos are distributed through mountain valleys at altitudes up to 725 m and in terrain glaciated as recently as late Wisconsinan time. Most are open-system forms; possible closed-system pingos are present at only a single locality in a northern valley. Some pingos occur on thick alluvial or lacustrine sediments, but many seem to be localized above near-surface bedrock and possibly are related to northeast-trending fracture systems. Pingos are particularly abundant in the Koyukuk and Chandalar drainage systems of the south-central Brooks Range, where they may be associated with structural features of regional extent.</span></p> application/pdf 10.2307/1550810 en INSTAAR, University of Colorado Pingos in the Brooks Range, northern Alaska, U.S.A. article