National Geographic : 1910 Jan
THE COAL-FIELDS OF ALASKA* With a Few Notes on the Mineral Wealth of the Territory THERE are two known areas of high-grade coal-the Bering River field, in the Controller Bay region, and the Matanuska field, north of Cook Inlet. The Bering River field, lying about 25 miles from tidewater at Controller Bay (see map, page 24), embraces 26.4 square miles underlain by anthracite and 20.2 square miles underlain by bitumi nous coal. The coal-bearing rocks trend to the northeast into the unsurveyed high ranges, and it is quite possible that there may be an extension of the coal-fields in this direction. Coal-beds varying from 6 to 20 feet in thickness are exposed in this region, with some local swellings, giving a much higher maximum thickness. In quality the coals vary from an anthracite, with 84 per cent of fixed carbon, to a semi bituminous, with 74 per cent of fixed carbon, and include some varieties that will coke. There has been much pros pecting of these coals, but in the absence of railways no mines have been devel oped, though a small output from one bed has been taken to the coast in barges. The Matanuska coal-field lies about 25 miles from the tidewater at Knik Arm, a northerly embayment of Cook Inlet. As Cook Inlet is frozen during the win ter, however, the distance to an open seaport must be measured to Resurrec tion Bay, on the east side of Kenai Peninsula, about 150 miles from the coal-field (see map, page 3). The known commercially valuable coals of the Matanuska field vary in quality from a sub-bituminous to a semi-bitu minous, with some anthracite, and are included in folded and faulted Tertiary (Eocene?) shales, sandstones, and con glomerates, aggregating 3,000 feet in thickness. The coal-beds vary from 5 to 36 feet in thickness, and the total area known to be underlain by coal aggregates 46'2 square miles. However, as much of the field is covered by gravels and none of it has been surveyed in detail, the coal bearing area may be much larger. The total area of what may prove to be coal bearing rocks is approximately 900 square miles. Up to the present time there has been no means of transporting this coal to market, so that no mining has been done, but many beds have been opened in prospecting. The anthracite from Matanuska and Bering rivers has no equivalent on the Pacific Coast, and it compares favorably with the Pennsylvania anthracite. It ought to be put into the San Francisco and other Pacific Coast markets at a cost far below that of Eastern coal, in which case it should have no difficulty in en tirely supplanting the latter. The Bering River semi-anthracite and part of the semi-bituminous coal from Matanuska is also better than anything that is being mined in the West. These coals are the equivalent of the Poca hontas, New River, and Georges Creek coals of the East, and are eminently adapted for use on warships and for other purposes for which a high-grade, pure, "smokeless" steaming coal is re quired, and for these purposes will com mand a considerably higher price than any coal now being mined on the Pacific Coast, or, if offered at equal prices, should readily drive the latter from the market. Part of these coals will produce an excellent quality of coke-better, in fact (except possibly in content of phos phorus, regarding which no data are available), than coke which can be pro- * From reports of Alfred H. Brooks, Chief of Alaskan Division, U. S. Geological Survey.