786 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



a few miles south of Kasilof River, and they do not appear again. These coal measures were 

 thought by Heer to be of .Miocene age, but Dr. DaU referred them to the Oligocene and gave a 

 Kst of plant and animal remains collected at Port Graham, among which are both Conifer^e 

 and broad-leaved trees, the total number of species amounting to 44. He says: "The deposit 

 appears to have formed at the bottom of a lake." 



Dr. F. H. Knowlton in the same report " gives a list of plant remains from the Kenai for- 

 mation collected by Dr. DaU in 1895, as well as those previously known from the same region, 

 and states that they are beheved to be of Eocene or Ohgocene age. 



Later, in speaking of the typical Eocene strata of Chichagof Cove, Dr. DaU >> says: 



"The only representative of the Eocene epoch known in Alaska previous to the Harriman 

 Expedition was the Kenai series (formation), which had been referred by Heer to the Miocene 

 and by others to the Eocene but which has of recent years been recognized as Oligocene by the 

 present writer and others." 



In the same pubUcation '^ Dr. Knowlton, after describing a coUection of fossU plants from 

 Kukak Bay, makes this statement concerning their age: 



"It is hardly necessary at tMs time to go into a history of the plant-bearing horizons of 

 Alaska. * * * It is sufficient to state that the named species above enumerated are typical 

 of the so-caUed Arctic Miocene, which is now regarded as of the age of the upper Eocene. The 

 species described in this paper as new are in various ways aUied to forms characterizing this 

 horizon, and I do not hesitate to refer this coUection to the upper Eocene." 



The determination of marine Oligocene invertebrates and upper Eocene floras 

 from nearly related strata may seem to suggest that there was a sequence of deposits 

 which included the two terranes, but Atwood's results of 1908 appear to indicate 

 that the Kenai plants are associated with marine Eocene fauna. (See pp. 783-784.) 

 Moffit and Stone continue: 



The Kenai formation as exposed in Kachemak Bay is composed of soft light-gray sand- 

 stones and clay shales, with numerous interspersed coal seams. Four partial sections of the 

 formation aggregate 1,763 feet of strata. * * * [They contain] seams rangmg in thickness 

 from a few inches to 7 feet. * * * The sandstones are medium grained, soft, Hght gray, 

 sometimes iron stained, and occur in beds from a few inches to 30 feet thick. Cross-bedding was 

 noted at one horizon. Some portions of the heavier beds of sandstone are hard and weather 

 out in nodular blocks. In these blocks the best-preserved fossil plants are sometimes found. 

 In one locality lenses of grit occur in a sandstone mass. The pebbles in the grit are smaUer 

 than one-half inch in diameter and are mostly quartz. DaU"* reports conglomerates in the 

 Kenai series on Kachemak Bay, but the author found none in the portion he visited. Sand- 

 stone at places grades into sandy shale. 



The shales of the Kenai formation on Kachemak Bay are all light^colored clay or mud 

 rocks, grading on one side into arenaceous shale and on the other into clay. The shales are soft 

 and crumbly on the outcrop and when wet become plastic. Beds of clay that have been baked 

 by the burning of coal seams are red and hard. Small blocks of gray hard limestone were found 

 at one locality and suggest that calcareous sediments in small amount may be contained in the 

 formation. Limestone was not seen in place. 



The abundant coal seams in the Kenai rocks of this field are all lignite. They vary in 

 thickness from mere streaks to beds several feet thick. Eldridge « counted 36 seams along the 



«Dall, W. H., Report on coal and lignite of Alaska: Seventeenth Ann. Rept. U. S. Geol. Survey, pt. 1, 1896, 

 p. 876. 



!> Alaska, geology and paleontology: Harriman Alaska Expedition, vol. 4, 1904, p. 101. 



« Idem, p. 162. 



"^Dall, W.H., Report on coal and lignite of Alaska: Seventeenth Ann. Rept. U.S. Geol. Survey, pt. 1, 1896, p. 789. 



« Eldridge, G. H., A reconnaissance in the Susitna basin, Alaska: Twentieth Ann. Rept. U. S. Geol. Survey, 

 pt. 7, 1900, p. 21. 



