AIRBORNE RADAR SOUNDING OF THE

Radar sounding is a technique used in recent years to determine the thickness of ice sheets and glaciers. A radar signal is transmitted through ice, a dielectric, is reflected from the bottom, and is received at some time after its transmission. The length of time which the radar pulse spends in the ice, the so-called "delay time of the pulse, " can be related empirically to the thickness of ice sheets and glaciers with a maximum uncer-tainty of approximately 2 percent without considering errors in positioning, electronics, and other conditions. Airborne radar sounding was used, in 1966, to sound successfully nearly 10,000 km of the Greenland ice sheet, penetrating the ice to a depth of up to 3,000 m. This method is rapid, mobile, and accurate when compared with more conventional techniques and should prove to be a most valuable tool for the study of the thickness of glacial ice