Wikipedia defines a moraine as:

A moraine is any glacially formed accumulation of unconsolidated glacial debris (soil and rock) which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past ice age. This debris may have been plucked off the valley floor as a glacier advanced or it may have fallen off the valley walls as a result of frost wedging. Moraines may be composed of debris ranging in size from silt-like glacial flour to large boulders. The debris is typically sub-angular to rounded in shape. Moraines may be on the glacier’s surface or deposited as piles or sheets of debris where the glacier has melted. Moraines may also occur when glacier- or iceberg-transported rocks fall into the sea as the ice melts.

The Altamont Moraine is a very large geological area.  GNIS lists this range as being in 17 North Dakota counties, 33 Minnesota counties and 21 South Dakota counties.  Some references show it also being in Wisconsin and Iowa, but there are many named moraines and their exact borders are defined in different ways.

Page 132 of "The Story of the Prairies, or the Landscape Geology of North Dakota" by Daniel Everett Willard originally published in 1906 says:

A Picturesque Group in Griggs County.  One of the prettiest groups of lakes in the State and surrounded by the most picturesque morainic hills is that in Griggs County, and also extending north into Eddy County.  The group consists of Lake Jessie, Addie, Sibley, Clear and Red Willow, besides many small ones, and also the North and South Washington Lakes in Eddy County, and Free People's Lake, on the Indian Reservation north of the Sheyenne River.  From Devils Heart Hill across the Sheyenne at the Morris ford to McHenry and Cooperstown is a continuous series of lakes and hills.  West of Cooperstown are the high, steep, rounded knobs of the Dovre Moraine, rising seventy-five to one hundred and fifty feet above the surrounding prairie, covered often thickly with large granite and limestone boulders, and among these hills are the silvery sheets of water of the lakes named.