williams. J CONCLUSIONS. 259 



along the Mackenzie River to the Arctic and about the shores of B ml 

 son Bay, are too fragmentary to admit of generalization. The Western 

 province has not been worked up with sufficient detail to admit of other 

 than broad generalizations. The correlations in these three provinces 

 were based upon purely paleontologic data. The other three provinces 

 are partly connected at their boundaries and roughly defined are great 

 basins, in which the more recent Carboniferous formations are partially, 

 at least, surrounded by the older Devonian rocks. 



The Appalachian province is separated from the Mississippian 

 province by a geological anticline called the Cincinnati axis, extending 

 from middle Tennessee in a northeasterly direction to near Sandusky, 

 Ohio, and thence across Lake Erie into Ontario, Canada. The Michigan 

 province is connected with both the Appalachian and the Mississippian 

 provinces by a common band of Devouian rocks running from Toledo 

 across to the southern end of Lake Michigan. 



In the center of the Mississippian province the Ozark Uplift occupies, 

 with Silurian and Archean rock, the southeastern third of Missouri and 

 parts of adjacent Illinois and Arkansas. The western edge of this 

 province is terminated by the overlying Cretaceous along an irregular 

 westward curving line connecting Omaha and Austin, Tex. The 

 northeastern or Acadian province is defiued at the opening of the last 

 chapter and exhibits an immense thickness of Devonian and Carbon- 

 iferous shales, sandstone, and conglomerates, with little limestone, esti- 

 mated at 9,500 feet of Devonian and 16,000 feet of Carboniferous. 

 Along the eastern and northeastern borders of the Appalachian the 

 thickness may be a third less, but the deposits are still arenaceous, with 

 some argillaceous shales and with little limestone. The arenaceous 

 deposits decrease on going westward for the whole Devonian until in 

 Iowa the total Devonian is estimated at 200 feet of shales and Mag- 

 nesian limestone. The Devonian is represented all around the Michigan 

 province by considerable limestone in its early stage, running up into 

 soft shales, then Lower Carboniferous sandstone and shales, and finally 

 a few hundred feet only of Coal Measures. Passing southwestward 

 along the Appalachian province, or from Iowa and Michigan south- 

 ward in the Mississippian province, the Devonian loses the calcareous 

 base and the arenaceous top and dwindles down to a black shale, varying 

 from one hundred feet or so in Kentucky to nothing in Southern Ten- 

 nessee and around the western and southwestern margins of the Ozark 

 Uplift. With this change from the complex Devonian formation of New 

 York to the simple black shale of Tennessee there is a corresponding 

 change in the Lower Carboniferous from arenaceous and shaly deposits 

 in Michigan, Ohio, and Indiana to limestones of over a thousand feet 

 thickness in the Mississippian province, separating the black shale 

 from the Coal Measures. 



With all these differences in the stratigraphy there are corresponding 

 differences in the faunas and floras, and as the geologists have surveyed 



