This paper summarizes the results of a detailed investigation by the U. S. Geological Survey in cooperation with the Kansas State Geological Survey, Kansas State Board of Health, and the City of Wichita. The geology of the area has been remapped, and several new formations have been established, including the Emma Creek formation of middle and upper Pliocene age, and a thick loess deposit. The hydrologic studies involved extensive test drilling and resulted in the development of a new groundwater supply for the City of Wichita.