An inner tube is positioned from an arm extended from the front of a snow tractor, within the tube is an antenna that is looking down into the snow/ice layer and transmitting information to monitors. According to CRREL Research Geophysicist Dr. Steve Arcone, “GPR is a radio method to image snow and ice stratigraphy. The system is operated by pushing the antennas in front of a small tractor, while the operator monitors the imaged strata on a computer screen. Crevasses are detected in advance by viewing reflections from the vertical crevasse walls.”