The Agua de la Piedra Formation (FAP, Spanish names include Estratos de Agua de la Piedra and Complejo Volcano-sedimentario del Terciario inferior) is a Late Oligocene (Deseadan in the SALMA classification) geologic formation of the Malargüe Group that crops out in the southernmost Precordillera and northernmost Neuquén Basin in southern Mendoza Province, Argentina.