PALAEOZOIC TIME — CARBONIFEROUS AGE. 305 



In England and Bohemia, also, examples of disturbances between 

 the Devonian and Carboniferous have been observed. 



But all these cases are small exceptions to the general fact that 

 the Lower Carboniferous and the underlying rocks are conformable 

 almost the whole world over. The epoch of transition was not an 

 epoch of general disturbance. There were extensive oscillations 

 of level, but in general they involved no violent upturnings. The 

 Carboniferous age opens with a period of marine formations, and 

 the beds accumulated, in most regions where they occur, as a regu- 

 larly-continued series. 



CARBONIFEROUS AGE. 



This age is divided into three periods : — 

 I. The Subcarboniferous Period (13). 

 II. The Carboniferous Period (14). 



III. The Permian Period (15). 



The Carboniferous age, both in America and Europe, commenced 

 with a preparatory marine period, — the Subcarboniferous; had 

 its consummation in a long era of extensive continents, covered 

 with forests and marsh-vegetation, and subject at long intervals to 

 inundations of fresh or marine waters, — the Carboniferous ; and 

 declined through a succeeding period, — the Permian, in which the 

 marsh-vegetation became less extensive, and the sea again pre- 

 vailed over portions of the Carboniferous continents. 



American Geographical Distribution. 



The rocks of the Carboniferous age lie at the surface over large 

 areas of North America. (See map, p. 133, in which the black 

 areas and those cross-lined or dotted on a black ground are of 

 this age.) 



A. In the United States: 



1. Over parts of Rhode Island and Massachusetts, between New- 

 port and Worcester. 



2. Along the Appalachian region from New York into Alabama, 

 and spreading west over half of Ohio, and part of Kentucky and 

 Tennessee, and a little of Mississippi. 



3. Over central Michigan. 



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