The southwestern corner of the State contains excellent beds of clay, deposited by the seas and now used for building materials and pottery. Two beds in the Dickinson vicinity, each containing approximately 29 million cubic yards, yield the finest clays in the State. A layer of yellow sand clay overlies the whitish plastic variety here; the two combine to form a number of colors, and have the added advantage of being free from iron. Plastic clay beds of importance, although not so valuable commercially as the Dickinson deposits, are found throughout the southwestern corner of the State. They yield one of the rarest and most valuable types of clay for pottery and other specialized purposes. Shales found near the western clay beds are used in the manufacture of cheaper building materials.
The discovery of two large bentonite fields in southwestern North Dakota in 1930 opened up a new mineral resource. This claylike mineral is used as a binding agent and filler in many commercial processes, such as the manufacture of soaps, paints, and cosmetics. The larger deposit—in the Little Badlands—covers 25 square miles and contains about 100 million tons of the mineral, while the Chalky Butte deposit near Amidon contains about 60 million tons. The beds are easily accessible, being uncovered in many places.
Extensive sodium sulphate deposits have been formed in old lake beds in the northwestern corner of the State, where the mineral-bearing waters have evaporated, leaving a deposit of sodium sulphate crystals. North of the town of Grenora, 1,150 acres are covered with sodium sulphate beds ranging from a few inches to more than 30 feet in depth. Miller, North, and McKone Lakes, near Alkabo, contain more than 20 million tons. Sodium sulphate, also known as Glauber's salt, is commercially valuable, especially in the pulp and paper industries. Owing to lack of knowledge of its existence in this country, it has been imported largely from Canada.
Although geologists have doubted that oil exists in commercial quantities in North Dakota, considerable interest has been shown in the wells near Marmarth in the southwestern corner of the State. Their proximity to the Montana oil fields increases the possibility of the success of these wells. Much interest has also been shown in the development of a potential oil field south of Ray in northwestern North Dakota.
Hidden beneath the earth's surface are other minerals deposited during the geologic formation of the various strata. These include fuller's earth, sandstone, granite, gneiss, and gold; but because of their limited quantity and inaccessibility, they are commercially unimportant. The glacial deposits are important because they include the sand and gravel used extensively for road surfacing. Some of the eastern lake beds contain marl, a clay from which Portland cement is made. The extent and purity of the deposits are not definitely known. (For discussion of industrial development of mineral resources see INDUSTRY AND LABOR.)
PLANT AND ANIMAL LIFE
North Dakota falls into three distinct zones of plant and animal life: the Turtle Mountain region and a few scattered areas in the Canadian, or cold, zone; the Missouri and Little Missouri Valleys in the upper austral, or warmer, zone; and the remainder of the State in the transition zone.
Because of its semiarid climate, the State has only 600 square miles of wooded area. Native forests are found chiefly along streams and lakes, and in the Turtle and Killdeer Mountains. Despite the limited forested area, a surprising variety of trees is found. Throughout the Red River Valley, Turtle Mountains, and Devils Lake region plant life is similar to the Minnesota type, while such trees as the elm, green ash, box elder, poplar, and cottonwood are also common.
Although the cottonwood's ability to withstand drought makes it one of the most desirable species of trees in North Dakota, efforts are being made in many towns to eradicate the tree because of the ubiquitous soft white "cotton" which floats from its branches like summer flurries of snow.
During the fall and early winter, the thickets of the northern Red River Valley are aflame with the highbush cranberry, which lent its Indian name to Pembina, first permanent white settlement in the State. Other berries grow profusely along all the eastern streams, and many families assure themselves of a winter supply of jams and jellies by picking the June berries, chokecherries, wild plums, and wild grapes. In the woods along the Missouri and Little Missouri grow trees of the Missouri type—the broadleaf cottonwoods, willows, ash, elm, buffalo berry, and flowering currant. A trace of the Rocky Mountain type of forest is found in the Badlands and on the buttes of the Little Missouri, where the yellow pine and red cedar grow.