Gully landforms caused by thermal erosion which have been observed in the north of Western Siberia are discussed. A new index is introduced to characterize volumes of material removed by thermal erosion; the area has been subdivided into regions on the basis of the index values. The main factors controlling the nature and distribution of thermal erosion are considered. It is shown that the process is most fully developed in the north within the arctic tundra zone; the size and volume of the gullies are at a maximum in this zone. Values decrease towards the south becoming lowest in the forest tundra and northern tayga. The zonal nature of the thermal erosion is controlled by the climatic parameters of the various zones; the northern regions are characterized by a maximum concentration of runoff (due to rapid snowmelt) and by an almost total absence of a developed root system, since most of the vegetation consists of mosses and lichens.