Cryogenic features in Canada and Hungary and their significance for past climate

Abstract

Pleistocene deposits were examined in the Paks, Bábolna and Mogyoród areas of Hungary. Contorted soil horizons resulting from cryogenic processes in paleosols were found in the sand deposits near Paks. Various wedge-shaped features and sand involutions were found in gravel deposits in the Bábolna and Mogyoród areas. Sand wedges, ice wedge casts (former ice wedges), and frost cracks filled with sand are commonly found in these gravel deposits. The average height of the sand wedges is 1 -2 m, but some are as high as 3 m. The sand in these wedges is vertically layered, suggesting that frost cracking occurred a number of times, with subsequent filling of the crack with sand material. Sand wedges, frost cracks and ice wedges all develop in permafrost environments, and are currently actively forming in the Continuous Permafrost Zone in Canada. Cryoturbated soils, on the other hand, occur in ail permafrost areas, but are most common in the Widespread Permafrost Zone and Continuous Permafrost Zone. Cryoturbated sandy soils, however, usually occur only in the Continuous Permafrost Zone in Canada. The well-developed sand wedges, frost cracks, ice wedge casts and cryoturbated soils found in Hungary suggest that the Carpathian Basin was a permafrost area during a cold, glacial part of the Pleistocene. At that time this area was most Likely underlain by continuous permafrost.