Pg. 5 (fig. 2), 7 (fig. 3), 10-11. St. Hilaire Formation. Gray (dry) and very dark gray (wet), unbedded pebble-loam. Consists of silt (38 to 46 percent), sand (30 to 40 percent), and clay 15 to 29 percent), and abundant pebbles and cobbles. Weak vertical joints common and result in a moderately columnar structure. Thickness 1 to 4 feet at type; thickness up to 20 feet southward. Its characteristic color makes it a useful stratigraphic marker. Overlies Marcoux Formation (new) with sharp contact; typically there is a cobble concentration or boulder pavement present. Underlies Red Lake Falls Formation (new) with sharp and gradational contact. Thought to extend into northeastern North Dakota, northwestern Minnesota, and southern Manitoba. Interpreted as a glacial sediment. Age is considered Wisconsinan or pre-Wisconsinan, based on stratigraphic relations.

Source: Publication.