This educational illustration explains the geology of the Ringold Formation, a major sedimentary deposit found throughout the Columbia Basin and Hanford Reach region of eastern Washington. The diagram identifies layers of gravel, sand, silt, and clay deposited by ancient rivers, lakes, and floodplains during the Miocene Epoch. The Ringold Formation sits beneath Saddle Mountains Basalt and helps scientists understand the environmental history of the region before Ice Age floods reshaped the landscape. This image is used by the REACH Museum to support geology and earth science education.