The Leaf Hills Moraines, sometimes called the Leaf Mountains, are a range of hills in west-central Minnesota. The land does not exhibit many characteristics of mountains, but nevertheless rises typically to a height of 100 feet (30 m) to 300 feet (91 m) above the surrounding farmland through the duration of its range, occasionally reaching higher than 350 feet (107 m). The name of this range of hills is translated from the Ojibwe Gaaskibag-wajiwan, which was interpreted by Gilfillan as “Rustling Leaf Mountains.” The name is also shared by Leaf Mountain Township, the two Leaf Lakes ("Gaaskibag-wajiwi-zaaga'iganan"), and the Leaf River ("Gaaskibag-wajiwi-ziibi"), all named for the hills. In turn, the hills in Ojibwe are named after Inspiration Peak ("Gaaskibag-wajiw"), the highest hill of this hill range.
The hills are described by Upham as "running southeast from Fergus Falls to the south line of the county and thence east and northeast to East Leaf Lake, a distance of 50 miles." Through their full extent in Otter Tail County, the hills have steeply sloped sides covered by prairies and deciduous forests, primarily maple and oak. In most regions these hills would not be considered mountains, but in generally flat Minnesota they are significant and unique features of the landscape, much more notable than in a really mountainous area.
The hills are formed by the convergence of the eighth and ninth marginal moraines formed by the Wadena and Des Moines lobes of the Wisconsonian glaciation. This moraine forms an arc about ten to twenty miles (16 -32 km) wide and 200 miles (320 km) long. It is composed of a huge volume of morainic drift up to 350 feet (107 m) thick, overlain with thin sandy soil as well as rocks and boulders.