Along the Cannon Ball, west of New England, are some excellent lignite exposures. Five and one-half miles west of this postoffice the following section is beautifully exposed in a cut-bank:

This exposure is continuous for 300 feet. A little lignite has been taken from this point by neighboring ranchmen.

Three miles farther west, under similar conditions, this series. is practically repeated, and the persistence of the seams to this point may be assumed.

On Coal Bank creek, which rises eight miles south of New England, and flows northeast into the north branch of the Cannon Ball, lignite outcrops at a number of points, and large springs and areas covered with scoria, both certain signs of the presence of lignite, occur. One four-foot seam of good lignite may be found four miles from the mouth of the creek, twenty feet above water level. Little prospecting has been done along. this creek, or along the river farther east, and there is strong probability that an abundance of lignite will some day be brought to light.

Along the south fork of Cannon Ball river lignite is said to abound. Some excellent seams are reported on Grand River, just over the line in South Dakota.

LIGNITE DEPOSITS OF EMMONS COUNTY.

Emmons county lies within the drift-covered area, and natural exposures that would reveal lignite seams are not common, except along the Missouri river, which forms its western boundary.

Near Livona, which is on the river, twelve miles south of Bismarck, some mining has been done. In Township 135, Range 75, the C. H. Edick mine has developed a seam two and one-half feet thick. The outcrops occurred near the bottom of a coulee, and the lignite is won by drifting. At the mine the

coal sells for $2.75 a ton, a price which shows the peculiar advantage in location. Southwest of Williamsport, in Township 135, Range 78, the Jesse E. Brindle mine at one time took coal from a two-foot vein.

Very little prospecting has been done of a sort that would reveal what lies below the thick covering of glacial drift. The county lies near the eastern border of the lignite area, but may be expected to contain considerable quantities of coal.

LIGNITE IN THE TURTLE MOUNTAINS

This plateau forms an eastern outlier of the Laramie series of North Dakota, and the strata beneath the glacial drift for four hundred feet are like those of Ward county, namely clays. and lignite. The lignite outcrops at a number of points, for post glacial erosion has been vigorous and many ravines are cut deep into the clays. The best known of the natural exposures are north of Dunseith, while many others back in the hills are said to have been reported to Captain Brenner of Belcourt by the Indians on the reservation. Outcrops should be looked for also

in the vicinity of Bottineau.

In 1886 a three foot seam which outcropped on a hill side two miles north of Dunseith was mined by drifting, and it was found that the seam dipped toward the north at an angle of twenty or thirty degrees. Subsequently a vertical shaft seventyfive feet deep was sunk further back on the hillside which encountered at that depth a seam said be twelve feet thick, lying fifteen feet above the lowest point of the sloping seam. There is little doubt that the latter owes its slope to an extensive slip and that the seam is really horizontal and will be found above the lowest point in the part that was subject to the slip; but it can not be possibly affirmed that the seam reported as found at the base of the shaft is the same one. If the thickness is reported correctly, and the two occurrences represent the same seam, the increase in thickness is very rapid.

At present residents of Dunseith are opening up these workings and the prospects for a successful mine are good. If the initial showing is satisfactory considerable work will be done this winter. Lignite will command a good price, for wood in Turtle mountains is becoming scarce, and freight rates to this section from the Ward county mines are considerable.

SUMMARY OF MINING METHODS

As the brief descriptions given in the preceding pages show, practically all the lignite of North Dakota is mined by three well known systems: the strip pit; drifting in on the seam; and shafts, vertical or sloping. The system that is in use at a given locality depends on two factors; the stage of development that the seam has reached, and the nature of the seam. The strip

pit system is the simplest, but a coal bank begun in this way generally passes with time into a drift mine. Later it may be

found desirable to abandon the drift and sink a shaft. Local conditions, however, may interfere with this natural development, arresting it before the second and third stages are reached. Where capital is sufficient and other conditions are favorable, the preliminary stages are omitted and a shaft is sunk at once.

The Strip-pit System.-If statistics in regard to all of the local mines worked on this system in the lignite area were available, it would probably appear that at least half of the total output of the state is mined in this way. The only expense in the form of equipment needed is a scraper and pick, and operations are usually carried on only during the winter when other work is not pressing. The wide distribution of the lignite, much of it near the surface, has made possible a local mine within ten miles of nearly every settler in the western half of the state. Often the lignite outcrops on his own farm and at times at his very door. A suitable natural exposure is chosen for operation, one were the overlying clay is not thick, where there seems to be a good body of coal of fair quality, and where there is an opportunity to dump the material removed from the coal at a low level. A hill side or a stream bank where the outcrop most naturally occurs offers these very conditions, and in these places most of the strip-pit or "scalp" mines are found.

The amount of stripping that can be economically undertaken depends on thickness and quality of the underlying coal, but ten feet may be regarded as a maximum where the coal is but six feet thick. In many localities where mining is carried on in winter the clay removed from the coal is dumped directly

into the creek bed and carried away during the high water of spring. Where fair wages are paid for labor and teams and the haul is short the cost of stripping is about ten cents a cubic yard. An acre of land bearing a seven foot lignite seam yields by the strip-pit system, about 8,000 tons. As the distance from the creek bed or into the hill increases the overburden grows, till this system is no longer profitable and it gives place to drifting.

Drift Mines.--The larger mines near the Mouse river, in Ward county and along the Northern Pacific railroad, are of this sort. Entries are run in on the coal, or beginning a short distance above it, slope down at an angle of ten or fifteen degrees till the coal is encountered, when the seam is followed. In all cases the room and pillar system is used underground. No lignite seam so thin as to make long wall mining advisable has yet been developed, except by the strip-pit system. Both single and double entry mines are to be found in the mining area, mines working double entry being more common. The lowest point in the mine is chosen for a "sump," and from this the water, which is generally present in some measure, is pumped, either vertically to the surface, or out at the entry.

Vertical or Inclined Shafts.--In mines where the equipment is expensive it is generally advantageous to sink a shaft to the lignite, though some seams, on account of overlying quicksand, present difficulties to this method of mining. It is possible to bring the coal from all points of the compass to the foot of the shaft, and the underground haul, an item of consideraole. expense, is greatly reduced as compared with the drift mine, where a semi-circle is the widest range for hauling. Where the depth of the mine is not great, as at the Washburn mine, a sloping entry may be recommended, since it obviates the necessity of elevators for the men aud gives easy access to the mine. Where the distance to the coal is considerable the vertical shaft, being shorter, is more suitable. The New Era mine, near Minot, will have a vertical shaft more than 300 feet deep when it reaches the lower or ten-foot seam. All underground work in these large lignite mines follows the room and pillar method. Instead of the ordinary double entry, the "butt entry" system is employed, in which the rooms are run directly from the main entries. As to size of rooms and pillars, there is a little variation in the lignite area from the practice common in the bitumi

nous coal regions. A map of the Washburn mine is given in Plate XXXI, showing the position of shaft and entries, and the arrangement of surface works.

Mining Machines in Lignite Coal.-Mining machinery of standard types is in successful operation in three of the lignite mines and most of the larger mines now under construction will be equipped with electric machinery. The freedom of the lignite seams from nodules of pyrites and other foreign substances renders them an especially fit field for the operation of undercutting machinery. At present the price paid for labor is higher than in older mining centers and it is more uncertain, the high price paid during harvesting resulting in the practical desertion of many of the mines. For all of these reasons the introduction of labor saving mining machinery is especially desirable. Undercutting machines and electric drills operate in lignite with about the same speed that is obtained in common practice in bituminous fields. Where the lignite is very solid "shooting from the solid" is effective and the advantages offered by the undercut mining machines are reduced. When the coal is badly checked however, the powder does not take hold along the cracks bringing down very little coal. cut machines may be introduced to great profit. given mine may differ in different parts sufficiently to render the undercut machine desirable at one point while its use offers no economy at another.

but blows out Here the under The lignite in a

Peculiarities of Roof and Floor. With but one or two exceptions it is necessary to leave from six inches to a foot of the lignite seam to form a roof, for the overlying clay is rarely tough enough to stand without the aid of this support. At none of the mines now in operation does sandstone occur above the coal in a way available for roof and at no point visited was a hard rock layer so advantageously placed, though one instance of this sort is said to exist in the vicinity of Glen Ullen where a sandstone layer a foot thick will make a substantial roof over an eight foot seam. From the given thickness of a seam therefore a deduction of six inches or more must be made in nearly every case, without regard to the purity of the coal, in computing its available thickness.

The floor is always a stiff, so called "fire" clay, though the application of this term to the under clay seldom has any reference to its ability to withstand high temperatures. The peculiar