The Distribution of Permafrost and Its Relation to Air Temperature in Canada and the U.S.S.R.

Abstract

P ERMAFROST is a widespread phenomenon in the northern parts of North America and Eurasia, and in Antarctica. Between 40 and 50 per cent of Canada's total land surface of 3.8 million square miles is underlain by permafrost. The total land area of the U.S.S.R. exceeds 8 million square miles of which 47 per cent is underlain by permafrost (Tsytovich 1958). Because of the great extent of this phenomenon knowledge of its distribution is of vital concern to both countries. The distribution of permafrost varies from continuous in the north to discontinuous in the south. In the continuous zone permafrost occurs everywhere and is hundreds of feet thick. The continuous zone gives way to the discontinuous zone in which permafrost exists in combination with some areas of unfrozen material. The discontinuous zone is one of transition between continuous permafrost and ground having a mean temperature of above 32�F. In this zone permafrost may vary from a widespread distribution with isolated patches of unfrozen ground to predominantly thawed ground containing islands that remain frozen. In the southern area of this discontinuous zone (called the zone of sporadic permafrost in other countries) the permafrost occurs as scattered patches, is only a few feet thick, and has temperatures close to 32�F