ANTHRACOLITHIC ROCKS OF KANSAS i6i 



the Carboniferous and the Permian; (2) In Russia we call Permo-Carbon the 

 intermediary horizons between the Carboniferous and the Permian systems, 

 characterized by a mixed fauna and flora, consisting of Carboniferous and Per- 

 mian species with the incorporation of some original species, which are met 

 with only in these layers. 



In Russia,^ as well as in western Europe, these intermediary horizons are 

 composed of layers previously looked upon partly as Carboniferous, partly as 

 Permian. 



For instance, in Russia in the composition of Permo-Carbon enter: The 

 Artinsk or pepper sandstone, which Murchison referred to the Carboniferous 

 system, as well as the limestone and plaster-stone of Kungur, which Murchison 

 referred to the Permian. Artinsk or pepper sandstone with Permo-Carbonif- 

 erous fauna composes the Artinsk-Stufe, the lower layers of Permo-Carbon. 

 It lies immediately on several kinds of limestone (Fusulina limestone and Schwage- 

 rina. limestone), which must be unconditionally related to the Carboniferous 

 system. On "Artinsk-Stufe" lies the " Kungur- Stufe " which forms the upper 

 layers of Russian Permo-Carbon. On these strata in Russia lie lime-marly 

 Platten which form the transition from the Permo-Carbon to the Permian system. 

 The Permian system itself in Russia begins with coppery limestone and red-clays, 

 on which directly follows the Zechstein-limestone. In Germany in the composi- 

 tion of Permo-Carbon equivalent to Artinsk and Kungur-Stufen, enter: Lebacher 

 Schichten (in Saarbriicken), Brandschiefer (in Saxony), Kohlenrothliegendes 

 (Bohemia). 



To make it clearer I give the following scheme: 



As to the question whether Permian-Carbon belongs to the Carboniferous 

 or the Permian system, that, from my point of view, is quite a matter of indiffer- 

 ence. But we generally connect Permo-Carbon with the Permian system.^ 



July 24, 1909 



I Krotow, Artinskische Etage; Geol. Forschungen am West-Abhange d. Urals; 

 Noiiz aiif d. Brief Herrn Nihitin iiber Permocarbon. 

 = Letter of February 19, 19 10. 



