Date of Award
Master of Science (MS)
Colgrove Butte is a flat-topped erosional remnant with a cap of rock area of approximately 0.845 square miles, rising about 200 feet above the surrounding Missouri Plateau in northwestern Hettinger County, North Dakota. Its upper portion consists of flat lying fresh water deposits of White River (Oligocene) age, containing beds of hard limestone, marls, argillaceous limestones, calcareous clays, clays and sands. It is everywhere covered by a mantle of top soil 6 inches to 3 feet 6 inches thick. Below this topsoil, extending over approximately two-thirds of the caprock area of the butte, is a bed of hard limestone averaging one foot in thickness, which is succeeded by alternate beds of marl, argillaceous limestone and calcareous clays down to a depth of 20-25 feet from the surface.
By rough calculations the weight of the uppermost limestone bed with a thickness of one foot was found to be 1,300,000 short tons, and its calcium carbonate content 80-90 percent. Bodies of rock extending three, six, and ten feet down from the bottom of the topsoil, and covering two-thirds of the butte area, were found to contain 61.5, 55.0, and 47.3 percent of calcium carbonate and weigh 3,820,000, 7,640,000, and 12,740,000 short tons respectively. Additional test holes need to be sunk into and through the caprock to determine more accurately the amount and grade of calcareous material available in the uppermost layers.
Manufacture of Portland cement from calcareous material at Colgrove Butte calls for the wet process, provided that sufficient supply of water can be economically developed.
Thorsteinsson, Thorsteinn, "Preliminary report on the geology of Colgrove Butte, Hettinger County, North Dakota" (1949). Theses and Dissertations. 296.