Paleoclimate Change Studies
A new dune-wetland succession from Mason County, Illinois, revealed that during the last deglaciation, eolian dunes associated with dry conditions prevailed during Heinrich 1 and Younger Dryas cooling intervals, whereas wetlands inundated the dune field during Bølling/Allerød warming intervals. The preliminary results of the paleoclimate change studies led by Hong Wang, Andrew Stumpf, Xiaodong Miao (all of Illinois State Geological Survey), and Thomas Lowell (University of Cincinnati) suggest an inverse pattern of rain belt distribution between the northern and southern United States in response to temperature fluctuations in the Northern Hemisphere, which provided constrains for accurate locations of polar jet streams. Results also suggested that by 17,700 years ago atmospheric circulations near the retreating Laurentide ice margin were tightly integrated with the global circulation pattern and no longer controlled by ice sheet geometry. Moreover, atmospheric changes over North America responded to temperature fluctuations in the Southern Hemisphere more rapidly than meridional overturning circulations in the north Atlantic.