Ledges State Park, about four miles south of Boone, is centered on a sandstone gorge carved by Pea's Creek, with cliffs and bluffs that make it one of Iowa's most distinctive landscapes. Designated as one of the state's first parks in 1924, it preserves rock formed about 300 million years ago and terrain cut roughly 13,000 years ago by glacial meltwater. Trails and many surviving Civilian Conservation Corps stone structures reflect later development, while older human history remains in burial mounds left by Sioux, Fox, and Sauk peoples. Repeated flooding, especially after Saylorville Lake, reshaped the lower park and removed many floodplain facilities.