356 



CAMBRIAN PERIOD 



The Cambrian in Other Continents 



Europe. 1 In Europe, as in North America, widespread defor- 

 mation before the beginning of the Cambrian converted large areas 

 of the present continent into land, and there is evidence that these 

 lands, like those of America, were subjected to protracted erosion 

 before the deposition of the Cambrian system. 



The Cambrian system of Europe, like that of America, is largely 

 clastic. Ripple-marks, cross-bedding, and sun-cracks are common, 

 showing that a large part of the Cambrian sediments were laid down 

 in shallow water, or on land. 



In Wales (Cambria), the country from which the system got its 

 name, and in Brittany, the system is very thick. In Scandinavia 

 and western Russia, on the other hand, it is thin, locally no more 

 than 400 feet. These differences probably mean that sediments 

 were being deposited in some places many times as rapidly as in 

 _^_^ others. The Middle Cambrian of Eu- 

 rope is more widespread than the Lower 

 or Upper, showing that changes in the 

 relation of sea and land were in progress 

 during the Cambrian period, shifting 

 the areas of erosion and sedimentation. 

 The Cambrian of western Europe 

 has been much folded, but in central 

 and eastern Europe, the strata are 

 essentially horizontal. Beds of clay 

 which are still plastic, and beds of sand 

 which are still uncemented, are known 

 in the undeformed part of the system. 

 Geographic changes of great importance 

 seem not to have marked the close of 

 the Cambrian, in Europe. 



Other countries. Cambrian rocks 

 occur in various parts of Siberia, China, 



Fig. 321. Glaciated stone 

 from the glacial beds at the 

 base of the Cambrian in China. 

 (Willis, Carnegie Institution.) 



India, Australia, and Tasmania, and in the northwestern part of 

 Argentina, but their distribution outside of North America and 

 Europe is but poorly known. 



Glacial formations, (i) In northern Norway, Lat. 70 8' N., 



1 The best summary, in English, of the Cambrian of Europe, is found in Geikie's 

 Textbook of Geology, 4th ed., Vol. II. 



