Ocheyedan Mound (pronounced O-cheé-den) is a large glacial hill known as a “kame.” The 24-acre preserve containing a portion of this large landform is located one mile south of Ocheyedan in eastern Osceola County. The Shuttleworth family purchased a 160-acre farm containing the mound in 1909. They donated the tract containing the mound to the Iowa Natural Heritage Foundation in 1983. In 1984 the mound was dedicated as a geological state preserve. Ownership was then transferred to the Osceola County Conservation Board.
Located on the western edge of the Des Moines Lobe landform region, Ocheyedan Mound is a kame which was formed during melting of the Wisconsin glacier some 12,000 years ago. It lies on the Bemis end moraine, a region of hilly ground that marks the farthest western advance of the Des Moines Lobe ice sheet into north-central Iowa. Kames are large, jutting masses of sand, gravel, and small boulders that were deposited by glacial meltwater streams pouring off the glacier, heaping dirt and stones to form a mound. Rocks of various sizes and colors are strangely intermingled on this mound, among them porphyry, granite, Sioux quartzite, and limestone.
This mound covers nearly 40 acres extending northeast to southwest over about a third of a mile. Its width averages several hundred yards wide, narrowing in places to only a few yards. With its summit 175 feet above the floodplain of the Ocheyedan River and 1,613 feet above sea level, Ocheyedan Mound is one of the highest points in Iowa. “Hawkeye Point,” located about four miles northeast of Sibley, is the state’s highest elevation at 1,670 feet above sea level.
