Quaternary permafrost and mountain glaciation in Kazakhstan

During the Quaternary there were numerous changes of climate in Kazakhstan. Cold epochs were replaced by moderate or warm ones and humidity varied. The most significant period of cooling occurred in the Middle and Late Pleistocene, when the permafrost of the northern and central plains of Kazakhstan merged with the permafrost of the mountains in the southern part of the country. Maximum mountain glaciation in Kazakhstan occurred in the Early and Middle Pleistocene. The first Eopleistocene (the transition section from Pliocene to Pleistocene) glaciation was caused by a significant humidity increase in the mountains together with moderate cooling; the second, in the Middle Pleistocene, was mainly cooling. In both cases tectonic elevation of mountain ranges played a major role. Appreciable changes of geocryological and glacial conditions were observed during the Holocene. For example, in the Little Ice Age there was a depression of permafrost belt borders in the mountains of up to 200-300 m, and small permafrost areas formed in the Kazakh Melkosopochnik (an area of old, low, rounded and isolated hills in central Kazakhstan). Also glacier fluctuations occurred. During the Quaternary, the high-altitude landscape zonation in mountains varied substantially. During glaciation, the forest belt narrowed, and in the Middle Pleistocene it was probably completely absent in the northern Tien Shan. Copyright (C) 1999 John Wiley & Sons, Ltd.