290 



PALEOZOIC TIME. 



The results exceeded in extent those that occurred over this same 

 region after the Carboniferous age. At this epoch, the raising of the 

 region of Maine above the sea, which had been carried forward 

 through its northern portion after the Corniferous, appears to have 

 been completed ; for no rocks later than Devonian are known to occur 

 over it. The existence of Helderberg rocks — probably Upper Hel- 

 derberg — in the Connecticut Valley has been stated on a former 

 page ; and it may be here added that the upper beds of the series, 

 now mica slate, gneiss, and quartzyte, may be of the Hamilton period. 

 The crystallization and upturning of these rocks of the Connecticut 

 valley, as well as those of Lake Memphremagog and the St. Law- 

 rence Valley, may have been a part of the events of this epoch. 

 At this time too, the region of eastern New York, west of the Hud- 

 son, which, during the Catskill period — that of the closing Devonian 

 — was subsiding and receiving thick marine formations, probably 

 emerged from the sea, leaving only a narrow southern margin of the 

 State under salt water. 



The other events of this epoch of disturbance, over North America, arc not made 

 out. In the county of La Salle, Illinois, and that adjoining it on the southeast, there is 

 a N. 33° W. anticlinal axis in the beds underlying the Coal-formation, as illustrated in 



Fig. 571. 



^73 



Fig. 571. But these underlying beds are Lower Silurian, including «, the Calciferous 

 formation; b, St. Peter's sandstone; c, the Trenton limestone; and it is not certain, 

 therefore, that the disturbance occurred directly before the Carboniferous age. In other 

 sections in northern Illinois, the Niagara limestone is included among the upturned 

 beds conformable to the Trenton, and hence the movement was not at the close of the 

 Lower Silurian like that producing the Cincinnati uplift. 



In Great Britain, Russia, and Bohemia, also, examples of disturbances between the 

 Devonian and Carboniferous have been observed, but not in Central and Southern 

 France. 



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

 iferous 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 for the most part 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 direct continuation of the deposits of the Devo- 

 nian. 



