426 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



more than 30 meters. The total thickness of Carboniferous may 

 be not far from 1,000 meters, as the maximum ; but the several mem- 

 bers vary greatly. Nathorst shows that throughout the whole sec- 

 tion deep-water deposits are wanting. The Kulm, in greatest part, 

 is of fresh-water origin ; the limestones, beyond doubt, were laid 

 down in shallow water during the long-continued slow subsidence 

 of the area. The fossil wood is of a type indicating a sub-tropical 

 climate. The deposits are conformable, the only irregularity being 

 due to overlap. 



Silesia. 



The Upper Silesian Coal Field. — This extremely important field 

 is between meridians 18° and 20° and is divided toward the southern 

 border by the 50th parallel. In greatest part, it is within Prussian 

 Silesia, but it extends eastwardly into Galicia and westwardly into 

 Austrian Silesia. The area is almost 4,000 square miles, of which 

 2,400 are in Prussia. The great economic importance of this field 

 has led to many careful and more or less detailed studies during the 

 last eighty years. According to Dannenberg,^^ the deposits have 

 been grouped into 



V. Saarbriick Stage Sohrau beds 

 IV. Nikolai bed 



- Karwin or Orzesch beds 



Ruda beds 



III. Sudetic Stage (Waldenburg) Sattelflotz beds 

 II. Czenitzer beds 1 



Loslauer beds r Rybnik beds Ostrau beds 

 Hultschun beds J 

 I. Lower Carboniferous Golonog beds Petrzkowitz beds 



Kulm 



The Ottweiler stage is wanting and the presence of Permian is 

 uncertain. The grouping is essentially that offered by Gaebler in 

 1898. Somewhat later, MichaeP^ used other terms : Instead of 

 Saarbriick he employs Mulden, as it occupies the central part of the 

 field; Satterflotz is replaced with Sattel-group, while the Ostrau 



25 A. Dannenberg, " Geologie der Steinkoblenlager," Erster Teil, Berlin, 

 1908, pp. 170-172, 180-197. 



26 R. Michael, " Die Gliederung der oberschlesische Steinkohlenforma- 

 tion," Jahr. k. k. preuss. Geol. Landesanst. Band XXII., 1902, pp. 319-340. 



