396 



PALEOZOIC TIME. 



a more gentle kind : eight coal seams are contained in this section, 

 each of the dark lines representing one. These are examples of the 



Fig. 699. 



Section of the Coal-measures, near Nesquehoning, Pa. 



condition of the whole anthracite region. The patches into which it is 

 divided, as shown on the map, p. 310, illustrate other effects of the 

 foldings ; for the whole, in all probability, was originally one great 

 area, continuous with that of western Pennsylvania. 



Section of the Coal measures, half a mile west of Trevorton Gap, Pa. 



The sections represented in Figs. 701, 702 illustrate the flexures of 

 the Paleozoic rocks, showing that the whole participated in the system. 



Fig. 701. 



Pig. 701 (by Lesley) is a section from the Schuylkill, along by Potts- 

 ville : the formations included in it embrace from the Potsdam sand- 

 Fig. 702. 



viv iv hi n ni iv v m vviYjy m „ 



Section from the Great North to the Little North Mountain, through Bore Springs, Va. ; t, t, 

 positions of thermal springs. 



stone (2) to the Coal formation (14) : the numbers indicate the for- 

 mations. The section in Fig. 702 (by Rogers) extends from the 

 Great North to the Little North Mountain, through the Bore Springs, 

 in Virginia : it has been partly explained on pages 93, 97. The for- 

 mations are numbered — II. the Calciferous ; III. Trenton ; IV. Cin- 

 cinnati ; V. Oneida ; VI. Clinton and Lower Helderberg ; VII. Oris- 

 kany sandstone and Cauda-galli grit. 



