Natural gamma-ray logging is the most versatile downhole geophysical method available for use in glacial and related terrain. Log profiles illustrate lithologic variation. They illustrate vertical sequences of glacigenic deposition as well as regionally recognizable till-statigraphic units. Expanded log profiles run at very slow speeds can illustrate cyclic variations in thick loess and in soil and soil-landscape relations. Recognition of depositional-sequence packages can provide an ultimate basis for a natural “genetic stratigraphic classification, a classification emphasizing whole events at all scales. Such log-based packages can provide the framework and the predictive models necessary for both regional and site-specific applications. These models can provide an objective understanding of variation that is critical to both engineering and hydrogeologic concerns.