The USGS published an update to the State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. It represents a seamless, spatial database of 48 State geologic maps that range from 1:50,000 to 1:1,000,000 scale, and this version includes updated data for six states, data for seven entirely new states, and numerous corrected errors since the preliminary dataset was launched. The USGS notes that, "the SGMC is not a truly integrated geologic map database because geologic units have not been reconciled across State boundaries. However, the geologic data contained in each State geologic map have been standardized to allow spatial analyses of lithology, age, and stratigraphy at a national scale." You can download a copy of the report here and the data can be downloaded from www.sciencebase.gov.