THE LAST GLACIAL ENVIRONMENT IN BERINGIDA - AN ATTEMPT OF MULTIDISCIPLINARY AND LONG-DISTANCE COMPARISON

The Beringian environment during the Late Pleistocene remains a matter of debate. A few sites across Beringida, a broader territory that incorporated the coastal lowlands and the vast shelf of the Arctic Seas from the Taimyr Peninsula to the Mackenzie River, provide various evidence of the past environment and climate during the Last Glacial. Most of it was covered by a treeless, grass-and-herb dominated vegetation, but the degree of aridity/humidity was quite different over that territory. The lower Kolyma area shows the most steppe-like variant of the environment that existed 17-13 ka. The insect fauna was dominated by steppe species, the summer temperature was a few degrees higher than present, and saiga antelope - a symbol of an arid grassland, was a member of mammal fauna. The climate is interpreted as highly continental, and the environment as warm tundra-steppe, that supported a rich community of mammalian grazers. In the Lena Delta area, the Last Glacial Maximum (LGM) assemblage was pinpointed in the continuous section with numerous AMS radiocarbon dates. The 20-15 ka insect assemblages of that region indicate the coldest tundra-steppe variant without true steppe species, but xerophilic plants were still abundant, and the summer temperature was probably at least not lower than today. According to the large collection of 14C dates on mammal bones, the LGM time was less favorable for mammoths and other grazers, and their numbers probably decreased, but they were still surviving even in the northernmost parts of the shelf land.

In the eastern area of the Bering Strait, it was shown that the presumably LGM environment was rather mesic, than xeric. Further east, into interior Alaska and Yukon, the climate was getting more continental, and the environment more xeric. Of critical importance is the most accurately dated LGM assemblage from the Seward Peninsula, Alaska (the Kitluk paleosol, buried under the 18-ka tephra). It was inferred that the LGM environment had many features similar to modern dry tundra, but in general it was a vegetation that had no complete modern analogues. A detailed comparison of the Kitluk fossil assemblages, supplemented by our new collection in 2003, with those from the Siberian side will hopefully better our understanding of the LGM environmental gradients across this huge space of Beringida.