THE MISSISSIPPIAN PERIOD. 



513 



Carboniferous period. This, it is to be noted, corresponds with the 

 sequence of events in North America. 



The Lower Carboniferous system of western Europe, like that of 

 North America, is largely of limestone. So true is this that the period 

 is sometimes knowm as the period of the Carboniferous limestone. 

 In Great Britain, these formations early received the name of 

 " mountain limestone/' and that name has frequently been used in 



Fig. 233. — Map showing the relations of land and water in Europe in the early Car- 

 boniferous period. The shaded parts represent areas of marine deposition. 

 (After De Lapparent.) 



connection with the corresponding formations in North America. The 

 Lower Carboniferous limestone seems to have extended continuously 

 from Ireland and Great Britain over northern France, where it has a 

 thickness of nearly 2500 feet along the base of the Ardennes, through 

 Belgium, and across the present valley of the Rhine into Westphalia. 

 Farther east, it passes into shale, sandstone, and even conglomerate, 

 collectively known as the Culm. 



Limestone, how T ever, is not the only formation of the Early Carbon* 



