1894. PROCEEDINGS OF THE NATIONAL MUSEUM. 237 



13 species; CEniugen 20 species; Oligocene 11 si)ecies; Miocene 33 

 species; Pliocene 15 species. 



By combining- a number of the above localities wliicli iiuiy l)e legiti- 

 mately taken togetber we have still more impressive results. Thus by 

 the combining of the Post Laramie beds of Colorado with the Livings- 

 ton beds of Montana, we have 13 species common to Alaska. The 

 union of the Mackenzie liiver and Port Union deposits gives L*l species 

 common to Alaska, while Cheenland, Spitzbergen, and Sachalin have 

 no less than 39 species out of the 55 s^Decies from Alaska. This last 

 result shows, if we are to place any dependence in fossil plants, that 

 the Horas of Alaska, Greenland, Spitzbergen, and the island of Sachalin 

 are so closely related as to lead to the nnavoidable conclusion that they 

 grew under similar conditions and were synchronously deposited. The 

 localities enumerated show that the circumpolar flora at that time was 

 practically similar and continucms. 



The coal-bearing beds of southeastern Alaska, to which Ball has 

 given the name of the Kenai group, are perhaps best exhibited on the 

 shores of Kachekmak Bay, Keiuii Peninsula, and Cook Inlet. They 

 api)ear, however, to be widely spread over British Columbia and over 

 the coast of Alaska and its neighboring islands. According to Dall* 

 the sequence of the rocks when undisturbed appears to be in descend- 

 ing order, as follows: 



1. Soil and Pleistocene beds. 



2. Brown Miocene sandstone, with marine shells, cetacean bones, and water-worn, 

 teredo-bored fossil wood. (Astoria group, Nulato sandstones, Crepidula bed.) 



3. Beds of conglomerate, brown and iron-stained, alternating with gravelly and 

 sandy layers, the finer beds containing fossil leaves of Sequoia .and other vegetable 

 remains. (Kenai group, I'ugalieds.) 



4. Bluish sandy slates nnd shales with a rich Miocene ]ilant Horn, interstratitied 

 with beds of indurated gravel, fossil Avood, andlignitic coal. (Kenai gron[».) 



5. Metamorphic quartzites and slaty rocks, illustrating the geologic series prob- 

 ably from the Jurassic to the Upper Cretaceous, Avith perhaps jiart of the Lower 

 Eocene. (Chico-Tejon.) 



6. Granite and syenite in massive beds, usually without mica and apparently in 

 most instances forming the "backbone" of" the mountain ridges or islands, but 

 occasionally occurring in intrusive masses. (Shumagiu granite.) 



The geological age of these coal-bearing rocks, from which most of 

 the plants enumerated in this i)aper came, has usually been regarded 

 as Miocene. Heer, who worked up the flrst considerable collection of 

 plants, referred them unhesitatingly to this horizon, and regarded 

 them as the equivalent of the Miocene beds of Greenland, Sintzbergen, 

 theBraunkohl of East Prussia, and the lower Molasse of Switzerland. 

 Lesquereux ami at tirst Newberry do not appear to have seriously 

 questioned their Miocene age. Of the 73 species enumerated by 

 Lesquereux in his latest publication on Alaskan plants, 21 are found 

 in Greenland and Spitzberg-en and 31 in the Miocene of other parts of 

 the world. These considerations show, as already pointed out under 



Bull. U. S. Geol. Survey, No. 85, p. 233. 



