338 



GEOLOGY. 



Foreign Ordovician. 



The Ordovician formations appear at the surface in various parts of 

 Europe, and they exist concealed by younger formations over consider- 

 able areas where they are not seen. Fig. 155 represents the general 



Fig. 155. — Diagram showing the relations of land and water in western Europe in 

 the Ordovician period. The shaded parts represent areas of marine sedimentation. 

 (After DeLapparent.) 



geographic relations of land and water in Europe during this period. 1 

 The submerged area represents in a general way the area where the 

 Ordovician formations are present. 



The known formations of this system, like those of the Cambrian, 

 are divisible into two geographic provinces, a northern and a southern. 

 The line or belt which separates them runs from the English Channel 

 on the west, across the plains of Germany to the heart of Russia on 

 the east. To the northern province belong the Ordovician strata of 

 the British Isles, Scandinavia, and Russia. To the southern belong 



1 DeLapparent, Traite de Geologie, quatrieme edition, p. 809. 



