The observed densities, assuming infinite homogeneous-horizontal beds, computed from borehole gravimetry were as much as 15 percent greater than those derived from gamma-gamma density logs in the lower portion of several clustered boreholes at the U.S. Energy Research and Development Administration (USERDA) Nevada Test Site. A model having a single high-density buried scarp to the west of the holes was constructed, the gravimetric density calculated, and the model varied in an attempt to improve agreement between measurement and calculation. Only slight improvement was obtained. Newly acquired geologic information made it possible to construct a more complex multiscarp model, providing much better agreement between measurement and calculation. In turn, this more complete model was refined with the help of the calculations.This method permits one to choose between qualitatively different models and, given a qualitatively correct model, to improve it quantitatively.