EAELIER TERTIARY (EOCENE AND OLIGOCENE). 787 



beach at Tyonek, varying in thickness from a foot to 15 feet, and Kirsopp " figures 73 seams on 

 the north shore of Kachemak Bay. Much of the Kachemak Bay lignite, especially that in the 

 lower beds, is hard and glossy, clean to handle, and tends to break cubically. The higher beds, 

 however, are dull and lighter and show more woody fiber. 



The thickness of the formation exposed in Kachemak Bay has not been determined, and it 

 is almost impossible of determination because there are stretches over which the beds can not be 

 traced. Anchor Point is near the base of the formation, but it is not known how far the coal- 

 bearing rocks extend beyond the head of the bay, except that coal has been found 15 miles up 

 Sheep Creek. Kirsopp '' published a section from Anchor Point to the head of the bay, includ- 

 ing 2,683 feet of coal-bearing measures. This section contains at least 126 feet of lignite in 

 seams over ? feet thick. Estimated roughly, there probably are about 1,500 feet of strata 

 between Bluff Point and the base of Coal Point. From Coal Point to McNeil Creek the dip is 

 strong and 3,000 feet may be a low estimate. From McNeil Creek to the top of the bluff at 

 Falls Creek at least 1,000 feet are exposed. Hundreds of feet of strata probably overlie the sec- 

 tion measured at Falls Creek and outcrop in the bluff north of the head of the bay. The writer 

 is inclined to think that 10,000 feet may not be a high estimate for the thickness of the Kenai 

 formation in the Kachemak Bay field. 



P 3. NXJNIVAK ISLAND AND YUKON DELTA. 



-pg^jpioa reported an occurrence of sandstones, probably Kenai, at Etolin Harbor, 

 Nunivak Island, but G. M. Dawson ^*'° describes the rocks as "cellular olivine dia- 

 base" and the island as composed of nearly horizontal basaltic flows. 



Cape Vancouver is a prominent point rising from the flats of the Yukon Delta 

 and composed of sandstone and sandy shales, capped by basalt flows in the higher 

 hills. Dawson says: 



The north shore of the cape, which alone was examined, forms scarped bluffs or cliffs, rising 

 from the edge of the sea, and presenting fine exposures of sandstones and sandy shales, well 

 bedded and dipping southward, at low and undulating angles. At the extremity of the cape 

 these beds appeared to be horizontal, and on the south side, though imperfectly seen from a 

 distance, they seem to lie at higher and more irregular inclinations. 



The sandstones, where examined, are gray, bluish and brownish in color, rather soft, and 

 sometimes nodular. They contain a few very thin and dirty seams of coal or lignite, of which 

 the thickest seen was only a few inches. There are also in the sandstones numerous carbona- 

 ceous fragments and occasional fossil leaves, of which a couple were collected. 



Sir William Dawson found these plants to represent Juglans acuminata and 

 assigned them to the Miocene. The horizon is now placed in the upper Eocene by 

 Knowlton. 



P 5. COOK INLET NEAR TYONEK. 



The exposures of the Eocene on the west shore of Cook Inlet, about 3 miles 

 south of the village of Tyonek, and the beltlike continuation of the strata to the 

 northwest at least as far north as Beluga River have been called Kenai and consist 

 of sandstones, shales, conglomerates, and some lignite. None of the material, so 

 far as known, is of marine origin. The deposits are such as to suggest estuarine 

 origin or sediments laid down on the land adjoining bodies of water. In the section 

 exposed along the shore of Cook Inlet, more than 2,000 feet of sediments are 

 shown. The beds are but shghtly deformed. The base of the formation is not 

 exposed, the eroded surface of the upturned beds being mantled by glacial drift. 



o Kirsopp, J., jr., Coal fields of Cook Inlet, Alaska: Trans. Inat. Min. Eng., London, 1901. 6 Idem, p. 3, 



