306 PALAEOZOIC TIME CARBONIFEROUS AGE. 



4. Over much of Illinois, and spreading eastward over part of 

 Indiana, southward over part of Kentucky, westward over part of 

 Iowa, Minnesota, Missouri, Kansas, Arkansas, and large portions 

 of the Eocky Mountain slopes. 



5. In Texas over parts of the more northern counties, being an 

 extension of the Arkansas coal region. 



6. About the summits of the Rocky Mountains, near several of 

 the passes ; around the Great Salt Basin in Utah ; in the Colorado 

 basin, New Mexico, and over some other parts of the Pacific slope 

 of the Eocky Mountains. 



B. In the British Provinces : 



1. Over much of New Brunswick and part of Nova Scotia. 



2. In the Arctic, over Melville and other islands between Grinnell 

 Land and Banks Land. 



The Coal measures cover a large part of most of the regions here 

 pointed out, the rest being occupied by the Subcarboniferous and 

 Permian, or by limestones and other barren beds of the Carboni- 

 ferous period. 



Excepting the areas west of the Eocky Mountains, the whole 

 pertain to three great regions or basins : — 



I. The Interior Continental region, including the Appalachian area on 

 the east, and stretching west to western Kansas, and perhaps still 

 farther, to or beyond the summit of the Eocky Mountains; for Car- 

 boniferous rocks probably underlie the later beds now at the surface. 

 It is divided into two parts by the Lower Silurian uplift about Cin- 

 cinnati and the region southwest. 



II. The Atlantic border region, including the New Brunswick and 

 Nova Scotia region, and that of Ehode Island, — also divided into 

 two parts, a northern and southern. 



III. The Arctic region. 



1. SUBCAEBONIFEEOUS PEEIOD (13). 

 I. Rocks : kinds and subdivisions. 



In the Interior Continental region the Subcarboniferous rocks are 

 mainly limestones. They are largely displayed in Illinois, Ken- 

 tucky, Iowa, and Missouri, and in the last they have a thickness 

 of 1200 feet. They also occur in Arkansas and Texas. In Ten- 

 nessee there are two groups : the lower, siliceous beds ; the upper, 

 limestone. In Michigan there are about 70 feet of limestone, 

 resting upon 480 feet of shales and sandstones. The great lime- 

 stone of the Carboniferous age over parts of the slopes and sum- 



