Despite considerable scientific research over the past twenty-five years there still remains much speculation and uncertainty concerning the origin of the so-called tabular uranium deposits of the Colorado Plateau. One particular hypothesis suggests that the deposits resulted from geochemical reactions at the interface between a relatively stagnant solution and a dynamic, ore-carrying solution which permeated the host sandstones. The present study was designed to investigate some aspects of this hypothesis, notably the nature of fluid flow and the relations between the ore deposits and the host sandstones.Field studies involved an investigation of the character and origin of the host fluvial sandstones and their contained uranium deposits and an examination of the textural and porosity-permeability patterns in similar Holocene fluvial sand bodies. Data from the Holocene sand bodies was used to construct realistic porous media models. These models were then saturated with a humic acid solution andean aluminum potassium sulfate solution, causing a visible humic acid precipitate to form at the interface of the two fluids. Finally, an existing numerical model was modified and calibrated for use in predicting the shape and location of the interface between the two solutions.