Abstract

Permafrost occurs when the ground remains at or below a temperature of 0^oC for a minimum period of two years. Permafrost occurs not only at high latitudes but also at high altitudes. Almost all of the soil moisture in permafrost occurs in the form of ground ice, which in turn occurs in several different forms. The quantity of ice in the ground varies widely. Permafrost and ground ice have had significant effects on the economic development of the North. It affects the energy and mining industries, as well as the construction of modern settlements and infrastructure elements such as roads, railways, airfields, and utilities.