DISTRIBUTION OF THE CARBONIFEROUS 409 



Upper 



Carboniferous 



Series. 



Lower 



Carboniferous 



Series. 



Pennsylvania Mississippi Valley 



4. Upper Productive Stage. ] 

 3. Lower Barren Stage. [ 2. Coal Measures. 

 2. Lower Productive Stage. J 

 I 1. Millstone Grit Stage. 1. Millstone Grit. 



2. Mauch Chunk Stage. 





4. Chester Stage. 

 3. St. Louis Stage. 



f Warsaw Substage. 

 " \ Keokuk Substage. 



1. Pocono Stage. jj Stage " [ Burlington Substa 



I 1. Kinderhook Stage. 



Distribution and Sequence of Carboniferous Rocks 



American. — In many parts of North America the Devonian was 

 followed so quietly by the Carboniferous, that it is very difficult 

 to draw the line between them, but in other regions notable geo- 

 graphical changes occurred. In the Acadian province, as at Gaspe, 

 and in Nova Scotia, New Brunswick, and Maine, there was a time of 

 upheaval and erosion toward the end of the Devonian, followed by 

 a renewed depression, in consequence of which there is an uncon- 

 formity between the two systems. When the Carboniferous period 

 began, most of New England, eastern Canada, and Newfoundland 

 was land, but the Gulf of St. Lawrence was still much larger than 

 at present, covering western Newfoundland, most of New Bruns- 

 wick, and part of Nova Scotia, and sending two long, narrow arms 

 southwestward as far as Massachusetts and Rhode Island. 



In the Interior Continental Sea wide-spread changes occurred, 

 but they were accomplished by slow oscillations of level, not 

 accompanied by violent disturbances. In the Rocky Mountain 

 region, there took place a great deepening and transgression of 

 the sea, and many of the land areas, the outline of which is still 

 very vaguely known, became extensively submerged. In conse- 

 quence of this transgression, the Carboniferous strata rest uncon- 

 formably, or in apparent conformity, upon Cambrian, Ordovician, 

 and Silurian rocks. From the Rocky Mountains westward Car- 

 boniferous rocks are much more widely extended than those of 



