Abstract A sequence of lithofacies clastic-ratio maps will reveal the stratigraphy of an aquifer. The use of these maps in conjunction with a study of the water-level fluctuations of wells and streams will aid in determining the relationship of surface water and ground water. In addition, these maps should indicate boundaries and water-table or artesian conditions of aquifers. They may also provide information concerning changes in quality of ground water. Introduction Lithofacies maps in combination with several types of ratio maps have been used in stratigraphic studies for many years. The value of these maps for the interpretation and reconstruction of paleogeography is unquestioned. Until the present, however, this concept of map making has not been utilized to a great extent for geohydrologic purposes. Hydrologists have the benefit of numerous complex formulas to be used in the determination of aquifer characteristics but the concept of an aquifer "constant in thickness, infinite in areal extent, homogeneous and isotropic" is one that normal does not exist in nature. Obviously, if aquifer characteristics are dependent on the structure, composition, and lateral and vertical changes in lithology of any water-bearing zone, then one must first determine as accurately as possible the, geology and then select the hydrologic formula that best conforms to the total picture. The collection of hydrologic data by means of pumping or aquifer tests is an expensive and time-consuming process.