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Asian climate became drier and more continental. Outward-fl owing winds from the high-
pressure systems that inevitably developed in winter transported dust particles (loess)
southwards towards the lowlands of interior China, and northwards towards the Eurasia
plains of Mongolia, Kazakhstan, and central and southern Siberia. The zonal westerly
winds were also diverted to the north and south of the Tibet uplift while at the same time,
the expansion of the northern hemisphere ice sheets led to an increase in the latitudinal
pressure gradients and to generally stronger winds in the mid-latitudes.
11.4. PLEISTOCENE PERIGLACIAL ENVIRONMENTS
OF HIGH LATITUDES
Intuitively, it seems reasonable to assume that the high latitudes experienced climatic
conditions during the Pleistocene that were similar to those of today. However, there were
two major differences. First, the ice-free areas of the high latitudes would have been in
relatively close proximity to the continental ice sheets. As a consequence, strong gravity-
induced winds, similar to those experienced today in the ice-free areas that surround the
Antarctic continent, would have been common. Evidence for this is provided by the wide-
spread occurrence of thick deposits of wind-blown silt in north-western North America,
Western Europe, and the lowlands of central Russia. Second, because of lowered global
sea level, many areas of high latitude would have been in more continental locations than
they are today.
In essence, the high-latitude Pleistocene periglacial environments would have been
dominated not only by a seasonal temperature regime, as today, but also by (1) greater
continentality, (2) greater aridity, and (3) more intense wind action.
11.4.1. Extent of Past Glaciations
The extent of Quaternary glaciations determined, to a large degree, the extent of the
Pleistocene periglacial environments of high latitude. Here, discussion is restricted to the
northern hemisphere because it is believed the Antarctic ice sheet has remained relatively
stable throughout the Quaternary.
In the northern hemisphere, continental-scale ice sheets developed over Eurasia
and North America on several occasions (Duk-Rodkin et al., 2004; Rozenbaum and
Shpolyanskaya, 1998a, b; Westgate et al., 2001). There is debate as to the extent of the
Early and Middle Pleistocene ice sheets, and several areas that are thought to have been
“never-glaciated” may have been covered by a thin veneer of cold-based ice rather than
being “ice-free.” This is probably the case for parts of the western North American Arctic
(Vincent, 1983, 1989), where the relative lack of cold-climate faunal and plant remains
that date to the time of the last glacial period suggests some areas may have been snow- or
ice-covered. Likewise, the “unglaciated” upland terrain of the southern Mackenzie Moun-
tains, NWT, which is thought not to have experienced glaciation for at least the past 350 ka
(Ford, 1996), may also have been covered by stationary, cold-based snow bodies.
The nature and extent of the Late-Pleistocene glaciations of northern Siberia and
northern North America and Greenland are much better known (Dyke and Prest, 1987;
Fulton, 1989; Prest, 1984; Romanovskii and Hubberten, 2001; Romanovskii et al., 2000).
Figure 11.6 is an international world map of glacier-ice extent during the last glacial
maximum (ca 18 000 ka) that shows the maximum extent of ice sheets and areas underlain
by permafrost. The extent of ice-free land takes into account the lower global sea level of
the time. Figure 11.6 shows the maximalist hypothesis of the extension of the Baltic-West
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