Stone State Park occupies nearly 1,600 acres on Sioux City’s northwestern edge, where bluffs and ravines along the Big Sioux River mark the northern end of the Loess Hills. Its steep ridges, prairie, oak woodland, and exposed Cretaceous lignite, shale, sandstone, and limestone create an unusual meeting of habitats known for native plants, wildlife, and marine fossils. The park’s northern section includes the 90-acre Mount Talbot State Preserve, later dedicated as a biological preserve after surveys in the 1980s and known for rich prairie and butterfly diversity. Also within the park, the Dorothy Pecaut Nature Center and trail system make it a major recreational and nature destination.