The most prominent feature in the Dunde ice record is the transition between the last glacial maximum (in the Pleistocene epoch) and the present Holocene epoch. Less negatived18O measurements
suggest that temperatures were cooler during in the Qinghai-Tibetan Plateau during the Pleistocene, while high particle concentrations show that conditions were much dustier. Very low concentrations of NO3-,
Cl-, and SO42 during the glacial period may
reflect higher precipitation rates during the last glacial maximum.
Paleoclimatologists often use information from other types of studies to test the hypotheses gleaned from ice core data. Geomorphological evidence shows that a large part of
the Qaidam Basin was covered by freshwater lakes during the last glacial; these lakes apparently began to dry up during the latter part of the last glacial in response to reduced precipitation or increased evaporation, and extensive deposits of
evaporite (minerals such as gypsum and halite formed when bodies of water evaporate and dissolved constituents precipitate) were formed.
NOAA Paleoclimatology Program and INSTAAR, University of Colorado, Boulder
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