It mainly consists of metamorphic sandstones, siltstones, and mudstones. Outcrops and eroded forms are the centerpiece of The Palisades State Park and Devil's Gulch at Garretson, and Falls Park in Sioux Falls. This crystalline granite is visible only in the northeastern part of the state near Milbank. It was exposed when erosion removed the overlying glacial till. Most of these shallow, localized bodies hold some water most of the time.
Smaller lakes undergo periodic filling and drying.
Most of these occur in depressions in hilly landscapes and are usually not connected to a larger drainage pattern. Officially, the largest of these glaciel lakes is Lake Thompson in Kingsbury county. Their maximum depth is seldom greater than 7m. A large volume of water from the melting glacier collected in east central South Dakota to form Lake Dakota, a very large lake whose depth exceeded 30m. Glaciel Lake Dakota had beaches and terraces marking several high water levels and occupied most of the James River valley north of Hitchcock.