Paleo Slide Set: Polar Ice Cores
Summer and winter core layers

There are two primary sources for this dust. During the dry northern summer, 
particulates from Arctic Canada and coastal Greenland are carried by wind currents and 
deposited on the Greenland ice sheet. In addition to this seasonal influx of dust, gigantic 
volcanic eruptions anywhere on the globe can also spew enormous quantities of dust into the 
atmosphere. Eventually, if atmospheric conditions are right, some of this dust may find its 
way onto the Greenland ice sheet. These dust layers are extremely important because they have 
allowed scientists to date the GISP2 core more accurately than most previous cores. 

Photo Credits:
Anthony Gow 
United States Army Corps of Engineers, Cold Regions Research and Engineering Laboratory.