Fults Hill Prairie State Natural Area in southwestern Illinois protects 997 acres near Fults, including a 532-acre hill prairie on the Mississippi River bluff above the American Bottom. Its steep limestone bluffs, ravines, and deep windblown loess support an upland prairie of grasses and forbs, with scattered fire-resistant trees such as bur oak. The site preserves uncommon Illinois species including big bluestem, cactus, skinks, fence lizards, and plains scorpions. Because most of its prairie was apparently never plowed during pioneer settlement, it remains unusually intact. Recognized as a National Natural Landmark, it is considered Illinois's largest high-quality, essentially undisturbed loess hill prairie complex along the Mississippi.