Undifferentiated metamorphics___ Slates and schists of the lower Talkeetna River. PLATE I. Topographic map of Matanuska and Talkeetna basins------ (pocket) II. Geologic map of Matanuska and Talkeetna basins.. III. A, Conglomerate Mountain, between Tsadaka and Eska creeks; B. Stratified breccias and tuffs east of Chickaloon Creek; C, Vertical-walled canyons in conglomerate on Chickaloon Creek ; D, Intercalated breccias and flows east of Chickaloon Creek IV. A, Lake in fault block, Conglomerate Mountain; B, Limestone at headwaters of Billy Creek; C, Rugged topography due to GEOLOGIC RECONNAISSANCE IN THE MATANUSKA AND TALKEETNA BASINS, ALASKA. By SIDNEY PAIGE and ADOLPH KNOPF. INTRODUCTION. The following report treats of the general geography, geology, and mineral resources of an approximately quadrangular area lying immediately northeast of the head of Cook Inlet. The region includes principally the Talkeetna Mountains and the Matanuska Valley, which separates these mountains from the Chugach Range on the south (Pl. I, pocket). The data for this report were gathered by the writers while they were attached to topographic parties engaged in mapping this region during the summer of 1906. The territory represented by the accompanying map embraces about 7,000 square miles. Necessarily much of the geology of so large an area must be generalized from the observations actually gathered along the line of travel. The principal resource of the region thus far developed is coal. As a portion of this coal is of high grade, comparing favorably with Pennsylvania bituminous coal, and, as anthracite of good quality also occurs in the region, the investigation of 1906 was directed to determining the boundaries of the various coal fields and to differentiating the ages of the various coal horizons. Attention was also paid to such metalliferous deposits as were encountered.. A summary of the results has already been published in the progress report for 1906. a The region considered was explored by the army expeditions of 1898. Portions of it have been investigated by members of the United States Geological Survey: Mendenhall explored Matanuska Valley in 1898; Eldridge explored Susitna Valley in the same year; Paige, S., and Knopf, A., Reconnaissance in the Matanuska and Talkeetna basins, with notes on the placers of the adjacent region: Bull U. S. Geol. Survey No. 314, 1907, pp. 104-125. Mendenhall, W. C., A reconnaissance from Resurrection Bay to Tanana River, Alaska, in 1898: Twentieth Ann. Rept. U. S. Geol. Survey, pt. 7, 1900, pp. 265-340. Eldridge, G. H., A reconnaissance in the Susitna basin and adjacent territory, Alaska, in 1898 Twentieth Ann. Rept. U. S. Geol. Survey, pt. 7, 1900, pp. 7–29. |