Stone State Park is a state park of Iowa, USA, located in the bluffs and ravines adjacent to the Big Sioux River. The park consists of in Woodbury and Plymouth Counties near Sioux City, and overlooks the South Dakota-Iowa border. Stone Park is near the northernmost extent of the Loess Hills, and is at the transition from clay bluffs and prairie to sedimentary rock hills and bur oak forest along the Iowa side of the Big Sioux River. A variety of prairie plants can be found on the steep slopes and ridges, including yucca, penstemon, rough blazing star, silky aster, and pasque flower. Wild turkey, white-tailed deer, coyote, and red fox are found in the park. Birdlife includes the turkey vulture, barred owl, rufous-sided (eastern) towhee, and the ovenbird. Exposed bedrock in the park is composed of lignite, shale, sandstone, and limestone, and dates to the Cretaceous period; it is rich in marine fossils. The park contains many miles of hiking and equestrian trails, and is a popular destination for day visitors, overnight campers, mountain bike enthusiasts, and picnickers.