the fact that the rocks in the less disturbed areas are found to contain only fragments of carbonized wood and small stringers of lignite. The Upper Jurassic strata lie in comparatively undisturbed attitudes, with prevailing low dips. Minor dislocations of the beds are of widespread occurrence. More extensive faulting is occasionally met with, as on Billy Creek, where faults of several hundred feet throw are revealed with diagrammatic clearness. Coal was seen at only two localities, on the head of Billy Creek and on the south fork of the Tyonek. At these localities the outcrops were obscured by mud and slide material, but the amount of coal represented was probably small. The coal found is a black lignite which checks on drying. Mendenhall reports thin beds of coal interstratified with the shales and sandstones along the south fork of the Nelchina.

ADJACENT COAL FIELDS.

Coal fragments are reported from Willow Creek. From Kashwitna River, at two points half a mile apart, and from Canoe Creek,

FIG. 4. Section on Billy Creek. 1, Sandstone and shale; 2, conglomerate; 3, greenstone amygdaloids; 4, basalt dikes.

7 miles north, a bed of lignite 7 or 8 feet thick is reported. This bed lies nearly horizontal and slopes very gently to the west. This appears to be an extension of the field of which Martin has compiled the following information: "

There appears to be a considerable area of coal or lignite in the Susitna Valley, in the vicinity of the mouth of the Talkeetna. Some of the exposures were seen by Eldridge, who describes them as follows:

"The third coal field along the main river, 4 to 10 miles above the Chulitna, appears in outcrops for a distance of 6 or 7 miles and is perhaps the exposed portion of an extensive area. The strata form bluffs 100 to 300 feet high, and consist of clays and sandstones-the former predominating-with coal seams from 6 inches to 6 feet thick. There are perhaps ten or fifteen coal beds exposed in the entire length of the outcrop. Their general dip is 5° to 10° SSE., with undulations. The thickness of the series exposed is perhaps 500 feet."

Op. cit., p. 26.

Eldridge, G. H., A reconnaissance in the Susitna basin and adjacent territory in 1898: Twentieth Ann. Rept. U. S. Geol. Survey, pt. 7, 1900, p. 22.

Other exposures in the same general district were described by Lieutenant Learned, who said: a

"As the party under my charge proceeded up the Susitna River, specimens of coal were found on the sand bars from time to time, but more plentifully as the forks were approached. On the way down the river an outcropping of coal was seen on the east fork of the Susitna River, about 2 miles south of the fork. The vein could not be measured, but as near as could be determined it was about 6 feet thick and of a poor quality.

"Upon entering the Talkeetna River coal was seen on the bars and banks, and the same coal was found in the Chunilna River. It was the main fuel used at the camp on the Chunilna River for about two months. The coal found there was a brown lignite of about the same grade as the best found in the vicinity of Tyonek. The vein was located first by Sergeant Yanert, and is noted on his map. It is about 6 miles above the mouth of the Chunilna, at the base of a cut gravel bank about 100 feet high. When seen by Sergent Yanert the water was clear and the vein could be traced across the river to the east bank. When I visited the vein the river was flooded and therefore very muddy. As near as could be determined by me the vein was 6 feet out of and fully as much more under the water, making it 12 feet thick, but Private Gamble, who had seen it in clear water, said it was at least 15 feet thick and perhaps much more, as it extended across the river, forming its bed, and there was no way of determining the thickness of that part forming the bed of the river. The vein is only slightly tilted, and comparatively easy to work if occasion should ever render it valuable. * * All of the coal found, when

*

consumed, gave a fair amount of heat, but left a large amount of ashes. Sergeant Yanert reported that he found another large coal vein on the Chulitna River of about the same grade as the Tyonek coal. It is doubtful if the coal found will ever have any commercial value, except such value as it possesses for fuel in the vicinity, and even that will be small, because of the timber found in the same localities. Enough was ascertained to show that there is plenty of coal of an inferior grade along the Susitna River."

The Cook Inlet coal fields have already been described by various authors. All existing information was summarized in 1902 by Brooks, who gave complete references to the earlier publications.

There seems little doubt that lignitic coal-bearing strata border the western base of the Talkeetna Mountains from Cook Inlet at least as far as Chunilna River, as is indicated by the successive float and outcrops reported from Willow Creek, Canoe Creek, Kashwitna River, and Chunilna River. It seems probable that these exposures are of sediments of Eocene age and of the same series of beds that were seen at other localities by Eldridge.

"Learned, Lieut. H. G., Reports of explorations in the Territory of Alaska, War Dept., Adjutant-General's Office, No. 25, 1899, pp. 162–163.

Brooks, A. H., The coal resources of Alaska: Twenty-second Ann. Rept. U. S. Geol. Survey, pt. 3, 1902, pp. 543-546.

Op. cit.

ANALYSES AND TESTS.

CHEMICAL AND CALORIMETRIC TESTS.

The samples collected by Martin were (with the exception of No. 3) all taken in a uniform manner. They were obtained by making a cut across a fresh face of the coal from roof to floor, cutting down only the coal which would probably be loaded and leaving out such impurities as could be separated in the ordinary practices of actual mining. They are thus supposed to represent the quality of the coal which would be mined from these seams. The parts of each seam which went into the sample are indicated in the local sections. No. 3 was taken from only the best parts of the seam and impurities were rejected which could be separated in practice only by very careful treatment, such as in "screened and hand-picked" coal, or possibly by some mechanical process, or by washing. The object of this section was to show, by a comparison of analyses Nos. 2 and 3, what could probably be gained in practice by such careful separation of impurities.

The samples that Martin collected were all analyzed by F. M. Stanton at the United States Geological Survey coal-testing plant at St. Louis, Mo. The methods of analysis are described in the reports of this plant."

The other analyses were gathered from a variety of sources. Nos. 4, 8, 10, 12, and 14 are based on duplicates of samples taken by Martin. The others are of varied character, some being fair representations of the seams and some random selections of the best coal.

The anthracite coal is represented by a single analysis (No. 1), which shows it (so far as this one outcrop is concerned) to compare favorably with some of the Pennsylvania anthracite.

Comparison of Matanuska and Pennsylvania anthracite.

a Ashburner, C. A., Ann. Rept. Geol. Survey Pennsylvania, 1885, p. 313.

A sample from Anthracite Ridge taken by the writers during the season of 1906 is here of special interest. (See No. 22 in table of ultimate analyses.) It will be seen that the coal has a fuel ratio of only 1.90, which places it in the bituminous class. The difference in

• Preliminary report on the operations of the coal-testing plant of the United States Geological Survey at the Louisiana Purchase Exposition, St. Louis, Mo., 1904: Bull. U. S. Geol. Survey No. 261, 1905, pp. 30–31. Report on the operations of the coaltesting plant of the United States Geological Survey at the Louisiana Purchase Exposition, St. Louis, Mo., 1904: Prof. Paper U. S. Geol. Survey No. 48, 1906, pp. 174-192.

Matanuska River, south side, 3 miles above Chickaloon Creek.

.do..

7,419

(c)

1.15

23.09

69.34

6.42

89

24.98

75.02

3.00