THE LIGNITE COAL FIELDS

OF

NORTH DAKOTA

EXTENT OF THE LIGNITE AREA

While thin seams of lignite have been recognized in the eastern part of the state and have been described* at the southern bend of the Cheyenne river, in Township 135, Range 54, Section 32, which lies about twenty-five miles southwest of Valley City, and at other points nearly as far east, workable seams are not found, except in the Turtle mountains, till the center of the state is reached. The plateau known as Turtle mountains is an outlier of the lignite area proper, which may be roughly bounded on the east by a line beginning at the northern boundary of the state and thirty miles east of the Minneapolis, St. Paul & Sault Ste. Marie R. R., and extending southeast to Harvey, thence south through Steele to the southern boundary. More minute study, aided by well borings which will doubtless be made as the country is settled, will probably shift this line east or west at certain points, thirty or forty miles. The state lines are its boundaries on the north, west, and south, while outside of the state the lignite continues in these three directions. Only this region, in which workable seams of lignite may reasonably be looked for, is included in this report under the term, lignite area. Even when so restricted it is of very great extent, equal to at least half of the state of

Ohio.

It is highly probable that lignite does not exist in seams of workable thickness in every part of this region, but it is equally probable that the fraction of the area lacking lignite in seams three or more feet thick is a small one, not more than one-fifth *Upham in Monograph XXV, page 92, United States Geological Survey.

Geol.-3

of the whole. These seams may not all be available, either on account of depth, or some other difficulty in mining and throughout a considerable part of the region are so thoroughly concealed by glacial drift that, without a knowledge of the underlying formations and of the surrounding country, their existence would be unsuspected.

TOPOGRAPHY OF THE LIGNITE AREA

The surface of the lignite area presents considerable variety. Areas that would be regarded as topographic types could readily be chosen from the moraines of Coteau du Missouri; from the older drift west of the moraine; from the Missouri valley; from the driftless area about Dickinson, and from the Bad lands.

THE WISCONSIN DRIFT PLAIN.

The extreme eastern portion of the lignite area lies within the coparatively levem1 plain of the Wisconsin drift, the deposit formed by the last great ice invasion. Like this plain throug out the eastern part of the state, it is moderately rolling, and rarely presents the extremely level surface that characterizes it in Iowa and Illinois. The interesting valleys of the Mouse and des Lacs rivers, which lie within this area, will be briefly described by Mr. Wood in his report on Ward county.

Rising rather sharply from the Wisconsin drift plain is the Coteau du Missouri, along the edge of which the lignite outcrops at a number of points which will be described in the subsequent text. The Coteau was studied along the Great Northern and Northern Pacific railroads, in a trip across country from Velva to Coal Harbor, and in a number of excursions back from the "Soo" road, and at all of these points its characteristics were quite constant. The rather sharp risc of its eastern face may be illustrated by the elevations of stations on the Great Northern. Des Lacs, 1902 feet above the sea, is on the prairie level, three hundred and fifty feet above Minot, which lies in the valley of the Mouse river. Berthold, twelve miles farther west, has an elevation of 2,087 feet. Wallace, six miles farther, is 2,187 feet high. From Wallace to Delta, a distance of five miles, an ascent of seventy-six feet reaches the crest of the Coteau. From this point the descent of the railroad is gradual to the west. crossing the outer or Altamont moraine of the Wisconsin drift, and reaching the level of the lower terrace of the Missouri river at Williston. The upland level, however, rises gradually toward the west.

THE MORAINES OF THE COTEAU DU MISSOURI,

Under this term is included a region twenty miles wide, lying about midway between the Missouri river and the "Soo" road in the northern half of the state, then with the river bending toward the south and continuing thirty or forty miles east of it, to the southern boundary. The region is strongly rolling, poorly drained, abounding in lakes and sloughs. This "hill country,' as it is commonly called, is well grassed and will ultimately become a thriving dairy district, though now practically without settlers. Although boulders are abundant they present no greater difficulties to agriculture and grazing than have been overcome under similar conditions in the older states.

THE OLDER DRIFT WEST OF THE COTEAU.

A definite attempt to correlate the older drift outside of the Wisconsin moraines, with the Iowan, Kansan or pre-Kansan which have been differentiated farther south, has never been made, and while some data bearing on the question was collected during the past summer, an attempt to solve this problem will be left for a later report, and the general term of "older drift" only will be used. This drift, which is well exposed in railroad cuts about Washburn and along the Missouri river from Nelson to Chilcot, is highly oxidized and above it at various points, notably near Wilton in Burleigh county, were deposits of fossil bearing loess. Its drainage is nearly perfect and the creek valleys wide, with very gradual slopes. The drift is generally thin and its topography is influenced largely by that of the underlying Laramine shales.

THE VALLEY OF THE MISSOURI RIVER AND ITS LEADING TRIBUTARIES.

The Missouri valley is the most significant topographic feature within the lignite area. In the narrowest sense it is three miles wide, and three hundred feet deep. In reality, however, the stream affects the slope of the land for a considerably greater distance on either side. In the valley proper are well marked terraces. Similar terraces also characterize the valleys of its leading tributaries. During the past summer these were studied along the Little Missouri, in southern Billings county. Here three benches, at varying heights above the flood plain, are well developed. The lowest is twenty feet above high water mark, and is composed of sand, loam, and gumbo, certain parts appearing very fertile, while other regions promise little to the