Cave-In Lakes in the Nabesna, Chisana, and Tanana River Valleys, Eastern Alaska

Abstract

Cave-in lakes resulting from ground caving following the thawing of permafrost have developed in areas underlain by fine-grained sediments in the Nabesna, Chisana, and Tanana River valleys of eastern Alaska. It is suggested that the vegetal cover has an important control over the presence of permafrost and that a cave-in lake is initiated by a break in this cover. Once a lake is formed, the banks retreat at a rate indicated to be of the order of a few inches a year. The recession of lake banks thus enlarges the lake and is responsible for a typical sequence of areal patterns of the cave-in lakes.