A Mount Sopris portable well logger was calibrated for gamma-gamma density and neutron porosity in dry geophysical-type boreholes in unfrozen materials. Since the hydrogen index of ice is less than that for water, the response of the neutron porosity for 100% ice reads as approximately 72% porosity. Thus, by cross plotting gamma-gamma density vs. neutron porosity, we can determine if the soils are frozen and estimate the unfrozen water contact.

Using this crossplotting technique, we believed that the hydrogen indices of natural gas hydrates, detected in oil wells on the North Slope of Alaska, provide a sufficient contrast with those of water and/or ice to provide a method of quantitative evaluation of hydrates in situ.

Logs of a hole drilled through a buried, artificial-ground ice mass showed that the natural gamma-log count rate decreases significantly in the vicinity of the ice, indicating that the natural gamma log could prove useful for detecting and delineating massive ice.

Calibrated logs were also used to estimate potential thaw consolidation and to follow seasonal variations in moisture content and bulk density.

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