182 ENVIRONMENT OF VERTEBRATE LIFE, ETC. 



From the Nabesna and White Rivers, Moffit and Knopfs reported the 



following section : 



Massive limestone. 



Shale, some tuffs, and lava flows. 



Basic lava and pyroclastic beds with some shale and limestone beds. 



The upper member, the massive limestone, is the one traced by Brooks 

 along the north base of the St. Elias Range to the Nabesna River through 

 the White River Basin (Professional Paper 45, p. 222.) 



In the Chisana-White River District Capps^ reports, 



Lava and pyroclastic beds, with some shale. 



Massive limestone with shale, thin bedded limestone and a little sandstone and 



conglomerate. 

 Lava and pyroclastics with a small amount of sediment. 

 Massive limestone of Skolai Creek with interbedded lava and minor amounts of 



shale and conglomerate. 

 Basic bedded lavas with little sedimentary material. 



The lower part of this section may be Devonian or Lower Carboniferous 

 as the Devonian shades into the Carboniferous; the upper two members of 

 the section are probably Pennsylvanian (Permian). The upper part of 

 the section is closed by an unconformity. 



The fossils are from one general zone "which seems the same zone as 

 that near Circle City described by Spurr (Takhandit series) or a closely 

 related one. I have made no specific determinations, since the fauna is 

 not to be correlated with the Upper Carboniferous of the Mississippi Valley, 

 but with the Fusulina zone of China, India, and the eastern slopes of the 



Urals." ^ 



Abundant fossils were collected in the Nabesna-White River region, 

 which were mostly referred by Girty to the Russian Gschelian.* It is very 

 probable that the massive limestone is the same as that in the Panhandle, 

 which has been traced into this region, and that the two lower series are the 

 equivalent of the lower beds in the same region.'' 



In general. Carboniferous rocks make up the north flank of the St. 

 Elias Range between the White and the Nabesna Rivers. Most of the 

 pyroclastic rocks were laid down in water, for they are in places interbedded 

 with sediments and locally contain fossils. It is probable also that some 

 of the lavas were discharged into the sea and cooled under water. The 

 tuffs and breccias are made up of material which was ejected violently 

 from volcanoes and which fell into bodies of water, there to be deposited in 



2 Moffit, F. H., and Adolph Knopf, Mineral Resources of Nabesna-White River District, 



Alaska, U. S. Geological Survey Bull. 417, p. 16, 1910. 

 2 Capps, S. R., The Chisana-White River District, Alaska, U. S. Geological Survey Bull. 



630, p. 39. 1916. 

 ' Girty, Geo. H., in Bulletin 630, just cited, p. 45. 

 ^ Moffit, F. H., and Adolph Knopf, Mineral Resources of Nabesna-W'hite River District, 



Alaska, U. S. Geological Survey Bull. 417, p. 20, 1910. 

 ' Idem, pp. 24-27. 



