Post-Eocene (predominantly Pliocene) continental sedimentary rocks of the Sacramento Valley, CA are up to 1,200 m thick beneath the valley. These rocks contain most of the fresh ground water in the valley, forming a key component of the total water budget for the valley. A 1974 study by the U.S. Geological Survey was an early attempt to develop detailed knowledge of the subsurface geology of the Sacramento Valley. The study delineated the configuration of the base post-Eocene continental sedimentary rocks of the Sacramento Valley and mapped the thickness of those deposits. This digital dataset contains spatial datasets corresponding to the contoured base and thickness of the post-Eocene continental sedimentary rocks as mapped by the U.S. Geological Survey's study of the Sacramento Valley. The structure contour and thickness maps were digitized and attributed as GIS data sets so that these data could be used in digital form as part of U.S. Geological Survey and other studies of the basin.