As ice forms, gasses and other materials are trapped in the layers that build up over time. This makes the polar regions time machines. With more than 500,000 years of snow and ice accumulation, the ice sheets are ideal places for paleoclimatologists to set up their tubular drills and extracct cores—long cylinders of sediment and rock—in order to read the history captured therein.

Image by: Office of Polar Programs, National Science Foundation