586 



GEOLOGY. 



Measures of Silesia, one bed attaining a thickness of 50 feet. 1 Here, 

 as elsewhere, beds of marine origin alternate with those which were 

 deposited on land, in marshes, etc. The constitution of the system 

 is such as to show that physical conditions corresponding to those 

 of the Pennsylvanian period in eastern North America were wide- 

 spread in western Europe. 



It will be remembered that the coal-bearing part of the Carbon- 

 iferous series in America is confined to the eastern half of the continent. 

 The chief areas of productive Coal Measures in Europe are in the western 



Fig. 272. — Sketch map showing distribution of coal in Great Britain (Kayser). 



part of the continent, another of the many rather striking correspon- 

 dences between the formations in those parts of these continents 

 which border the same ocean. Fig. 272 shows the distribution of 

 coal in Great Britain, and 272a, in the Lower Rhine basin. In 



1 Idem, p. 1054. 



