This unique natural feature, managed be The Nature Conservancy, must be seen to be appreciated. As you arrive, all that's visible is a long stretch of meadow. A walk along a trail brings you to the lip of the largest "kettlehole" in Iowa, and one of the largest in the nation! Kettleholes are formed when a chunk of a receding glacier (ours being about 12,500 years ago) breaks off and melts slowly in place. The result is a steep-sided bowl-shaped depression with a pond due to snow and rain accumulation (no water outlet or inlet). To the west is a breath-taking view of the Little Sioux River valley. The Nature Conservancy and Iowa Lakeside Lab. have studied the area extensively, identifying 326 plant species! The preserve is located of 210th Street, two miles west of Hwy. 86 (turn at Shuck's Bait and Tackle.)