THE DEVONIAN PERIOD. 441 



The Foreign Devonian. 



The continent of Europe. — At the close of the Silurian there seem 

 to have been more considerable geographic changes in Europe than 

 in America, for the Devonian system is there more commonly uncon- 

 formable on its base. This is especially true in the northern part of 

 the continent. When these geographic changes took place, a num- 

 ber of inclosed or nearly inclosed basins containing inland water- 

 bodies appear to have been developed in northwestern Europe. This 

 conclusion is based on the character of the deposits made in this part 

 of the continent, and especially on the fossils which they contain. 

 It will be seen that in a general way the phenomena on opposite sides 

 of the Atlantic corresponded, for considerable areas in America likewise 

 suffered warping, and similar inland basins of water or other lodgement 

 areas came into existence. 



During the progress of the Devonian period, the European conti- 

 nent was progressively submerged, as is shown by the fact that the 

 Middle and Upper Devonian formations are more wide spread than the 

 Lower (Fig. 202). In this respect, also, the phenomena of Europe are 

 in partial correspondence with those of America, though the Middle 

 and Upper Devonian of Europe overlap the Lower, and rest on older 

 formations more commonly than in America. 



In keeping with the geographic changes which the distribution of 

 the Devonian formations of Europe indicates, the Lower Devonian 

 strata of western Europe are for the most part such as to imply a 

 progressive advance of the sea on the land, but not without oscillations. 

 The greater abundance of limestone in the Middle Devonian shows that 

 the waters were clearer than in the earlier stage of the period, while the 

 wider distribution of the Middle Devonian, as compared with the Lower, 

 points to less extensive areas of land whence sediments could be derived. 

 As in America, the Upper Devonian of western Europe is more largely 

 of clastic material than the Middle, though it also contains some lime- 

 stone. 



Though the Devonian formations are widely distributed on the 

 continent of Europe, they do not appear at the surface over any large 

 area, except east of the Baltic in Russia. A lesser but still consider- 

 able area of Devonian appears in the basins of the Rhine and Moselle 

 rivers in western Germany, and in the adjacent parts of Belgium 



