THE AGE OF ANTHRACOLITHIC ROCKS 723 
and beneath it the “Middle Carboniferous.” The Artinsk is con- 
sidered as a subdivision of the Permian. 
The part of the section of particular interest to us is the portion 
including the “Cora,” Schwagerina, and Artinsk zones. The rela- 
tionships of these Upper Carboniferous beds of the Urals to the 
Artinsk is clear. The sandstones and conglomerates of the latter 
rest directly upon the calcareous deposits of the former. As has been 
so well shown by Krasnopolsky, the Permian period of eastern Russia 
is especially characterized by the uplift of the Ural Mountains from 
a series of islands to a continuous mountain chain. In the northern 
part, the Ural-Timen region—including the Timen Mountains— 
it was rapid and sandstones and conglomerates on the western flanks 
were the result. This permits a sharp differentiation of the deposits. 
In the southern region this sharp distinction is impossible as the uplift 
was very slow and the effects less noticeable, gypsum and dolomites 
being about the only lithologic indications of the changing conditions 
in the Donnez basin. In the north there is a sharp differentiation 
of the fauna in response to the sharply changed physical conditions, 
while in the south the differentiation is correspondingly more gradual 
and is produced by the mingling of the northern species of the Artinsk 
with the open-sea fauna of the Carboniferous. This makes the line 
between the Permian and Carboniferous harder to draw in the 
southern region. As Krasnopolsky argues,’ the place to draw the 
line is with the first appearance of the Permian species. The con- 
ditions in northern Oklahoma, Kansas, and Nebraska were very 
similar to those of the southern Ural region. 
As Rothpletz? has pointed out, and as further discussed by Diener,’ 
the arenaceous fresh- and salt-water deposits of the Ural-Timen 
region and the Zechstein are not the normal open-sea deposits of 
the Permian period, but somewhere those conditions existed in 
which the percentage of Carboniferous elements in the fauna would 
be larger. They also point out that these deposits probably are to 
1 Mem. Geol. Comm. Russ., Vol. IX, pp. 506 ff. 
2 Rothpletz, ““Die Perm-Trias u. Juraform. auf Timor, etc.,’’ Paleontographica, 
XXXIX, pp. 57 ff., 1892. 
3 “Diener, Himalayan Fossils,” Mem. Geol. Surv. India, Pal. Indica., Ser. XV, 
Vol. I, 1899-1903. 
