In most U.S. locations, students don't have ice in their soil; only students in Alaska have permafrost. Permafrost is any soil or surface deposit in an Arctic or alpine region at some depth below the surface at which the temperature has remained below zero degrees Celsius (32 degrees Fahrenheit) continuously for a long period of time. Next, students used Google Earth and the NSIDC file on permafrost to explore the types of permafrost and their distribution.