The moment method was used to describe and map the vertical variability of fresh-water sands within the Cretaceous aquifer systems (Lower Cretaceous, Coker-Massive, Gordo, Eutaw-McShan, Coffee, and Ripley) in a 20-county area in northeastern Mississippi. The position and thickness of the fresh-water sands were determined from a study of 126 electrical logs of water wells and oil tests. The distribution of the sands in each system was described by calculating moments using the thickness of the sand as the moment weight and the distance to its center as the moment arm. The moment data were used to define the center of gravity, standard deviation, skewness, and kurtosis, and these statistical values were contoured to show the areal variation. The contours for the center of gravity tend to parallel the dip and strike of the formations, and the standard deviation reflects the range of sand occurrence within the aquifer system. (WRSIC abstract).