The coal measure beds are made up of sandstones and carbonaceous shales, the shales predominating by a large margin. Limestones, dolomites and hard calcareous beds are conspicuously absent.

The structural conditions found in the coal fields are very largely responsible for the distribution of the coal and the economic importance of the beds. The formations making up the Arkansas River Valley, occupying as they do the lowest portion of the regional syncline, have been considerably folded, twenty-three major anticlines having been mapped in the coal-bearing area. This folding is reflected in the topography of the region by numerous east-west ridges which usually rise about 75 or 100 feet above the valley floor. Many of these are twenty miles or more in length. Many of these folds have been eroded and faulted and this condition has not infrequently been the cause of the termination, discontinuity, and thinning out of the seams and has been a contributing factor to the cost of mining. These features have also been largely responsible for the division of the field into a series of separated mining districts.

The coal increases in hardness in a fairly consistent manner from the western Arkansas line eastward, and contains about three to six times as much fixed carbon as volatile combustible matter in the western portion and from seven to nine times as much in the eastern. It thus grades from bituminous through semi-bituminous to a semianthracite. About 15 per cent of the coal produced is semi-anthracite. The following table shows the increase in the ratio of the fixed carbon to the volatile combustible matter in the coal from the west end of the field to the east.

One of the most commonly used classifications of coal is that proposed by P. Frazer, Jr. This is based on the relation between the amount of fixed carbon and the volatile combustible matter (fuel ratio) in the coal, and is given as follows:

Thus, an anthracite is a coal containing more than 12 times as much fixed carbon as volatile combustible matter, etc. This table does not provide for lignite which has a fuel ratio of less than 1. As understood by the trade, the limits are usually somewhat lower than these given.

Arkansas "anthracite" coals have fuel ratios from about 6.5 to 8.5, semi-bituminous from 4.5 to 6.5, and bituminous usually about 3.

The following table' gives a series of analyses according to the U. S. Geological Survey Fuel Testing Plant.

Laboratory coking tests made with Arkansas coals have indicated that some of the coals would probably coke. In practice, most of the Arkansas coals seem to be naturally non-coking, although it has been determined that the coals can be made into coking coals by the addition of pitch. U. S. Geological Survey tests show that Jenny. Lind coals will make good coke in practice when mixed with 8 per cent pitch.

'Briquetting tests with Arkansas coals carried out by the U. S. Geological Survey have indicated that when 6 to 10 per cent pitch is added to slack coal that it can be made into high grade fuel.

Steaming tests shown by the following table indicate that Arkansas coals have high efficiency when used to evaporate water in commercial boilers:

Survey.

Taken from U. S. Geological Survey Bulletin 326, 1907, page 103.

1Professional Paper No. 48. Part III. 1906, pages 1389-1472. of the U. S. Geological

co Pounds

of

Coal

Per Hour Per Indicated H. P.

Pounds

JO

Coal

Used Per Electric
H. P.

Hour

Arkansas coal has a relatively high heat value, it is clean to use, and burns with comparatively little smoke. According to the U. S. Geological Survey tests, no coal has been found in the United States west of West Virginia which is of as good quality.

Mining and Production

Coal has been mined in Arkansas since 1840, although active production did not begin until about 1880. More coal, 2,670,438 tons, was produced in the year 1907 than in any year in the history of the State. The value of this coal, however, was only $4,473,693 on account of the low unit value of $1.67 per ton. In 1925, 1,455,118 tons were mined, which was less than half of the 1907 figure, but this had a value of $5,700,529, which is 27 per cent greater than the total value of the 1907 production, as the 1925 unit value was $3.91 per ton.

The coal reserve of Arkansas has been estimated at *850,000,000 tons, assuming an 80 per cent recovery. Much of this estimated reserve, however, lies deeply buried, and if recovered will be expensive to mine. The coal fields of the State have not been completely surveyed as yet and it is possible that other areas associated with the coal measures will add to the coal reserve.

The larger portion of the Arkansas coal produced is consumed by the railroads and the remainder by domestic consumers, principally in northern and western markets, and this supply is contributing much to the commercial development of the Middle West. The transportation facilities in the coal district are good. The following railroads run through the mining area: Missouri Pacific; Chicago, Rock Island & Pacific, St. Louis & San Francisco, Midland Valley, and Kansas City Southern.

+Coal Production by Counties, June 30, 1924-June 30, 1925

*Arkansas Geological Survey Report, 1910, "Coal Mining in Arkansas," by A. A.

Steele.

Report of State Coal Mine Inspector for 1925.