GEOLOGY OF ANTHRACITE REGION

In many parts of the anthracite region one can find two beds separated by a small parting. This condition immediately causes trouble, for the parting may be of such a character that one bed can not be mined before the other and a reasonable recovery made from the second mined bed. The parting may be small, yet economical mining of the two beds at the same time may not be possible, as the expense of handling the rock may be too great. One bed may have contained a particularly high grade of coal, whereas the other bed may have been of a poorer quality that was unmarketable when the first bed was mined. Examples of mining under the difficult conditions that exist are discussed later.

From a point on the Susquehanna Eiver near Pittston to a point below Nanticoke, a distance of about 18 miles, extends the so-called Buried Valley of the Wyoming. This valley is about 1 mile wide at its widest part, is 50 to 350 feet deep, is filled with water-bearing glacial drift, and contains large amounts of quicksand. Coal beds often outcrop in this valley, and their mining is exceedingly dangerous. It is unsafe to approach too close to the outcrop or even to mine the beds unless the cover is thick enough to make mining safe. Furthermore, the roof must be permanently supported to forestall danger of breaking, for in that event there would be inrushes of water, the mine workings would be flooded, and the lives of the men would be in danger. Up to the present, therefore, no second mining or longwall work has been attempted in this area.

INFLUX OF WATER

Another feature which influences the mining methods used to some extent is the amount of water to be handled. A survey of the whole anthracite region showed that 10.9 tons of water have to be handled for each ton of coal mined.

LACK OF INFORMATION

The meager information the various operators possess on the working of thin beds by other companies has greatly retarded the development of thin-bed mining. Most of the new methods used in the anthracite field have been developed at individual collieries, and occasionally the data that have been obtained at one colliery of a company have not been utilized at another colliery of the same company when a similar bed was opened.

Until an exchange of ideas between engineers of different companies is established present-day conditions will probably continue. A concerted drive for better mining methods, rather than improve

bring the greatest results in the shortest possible time. Every day that lapses before such a concerted effort is made means that so much more coal has been produced and that so much more territory is rendered unsuitable for the application of the most modern technique; in consequence the coal is produced at a cost that is higher than is warranted, and the percentage of recovery is less than it should be.

LACK OF FORESIGHT

Lack of foresight has probably been one of the greatest factors in increasing the cost of anthracite. In only a little more than 100 years production has increased from 555 tons to over 90,000,000 tons, so the blame for lack of foresight can hardly be placed upon the early operators. Even in 1870 the annual output was only 14,172,004 tons, and at that rate the supply of anthracite was sufficient for more than 1,000 years. In 1890 the production was only 44,986,286 tons, about one-half what it is now.

Lack of foresight in planning development has wasted millions of tons of coal which have been put in such a condition that production is possible only at a prohibitive figure. First mining was considered the only available profitable way of getting out the coal; therefore hundreds, and possibly thousands, of miles of gangways were driven and the chambers and breasts turned off and driven where the coal was good. If the coal became poor, development stopped, as the market would not take inferior grades. If the coal in any section was exceptionally good, that section was gutted to the detriment of near-by or overlying workings.

"Why worry? The supply is inexhaustible, more than we or our great-grandchildren can ever use," the operators said; but the tremendous rate at which the industry has increased indicates that the coal measures, particularly in some areas of the Northern and Eastern Middle fields, will be practically exhausted in 50 years.

Bate of recovery.—This lack of foresight has not entirely ceased, unfortunately for the region. The report of the United States Coal Commission to Congress indicates that obsolete mining methods are still employed by some operators, particularly in certain sections of the anthracite region. The figures in this report indicate that the rate of recovery for the Southern field is 49 per cent, the Western Middle field 58.1 per cent, the Eastern Middle field 69.4 per cent, and the Northern field 67 per cent. The weighted average for the whole anthracite region is 61.1 per cent.

Table 11 shows the rate of recovery for beds that are less than 5 feet thick and compares this rate with the average for the region and the average for the thicker beds. The figures indicate the re