IOWA ACADEMY OF SCIENCES. 55 



CARBONIFEROUS FORMATIONS OF THE OZARK 



REGION. 



BY CHARLES R. KEYES. 



The term Ozark, as now generally understood, applies to all 

 the broad dome-shaped and mountaineous area, lying in south- 

 ern Missouri and northern Arkansas chiefly, and extending 

 from the Red to the Missouri river, and from the Mississippi 

 to the Neosho. In this sense the name is used in the present 

 connection. For a long time the Ozark uplift remained a region 

 about which less was known geologically, than perhaps any 

 other part of the North American continent. Of recent years, 

 however, so many new facts have been obtained concerning the 

 formations of the northern part of the area that a very com- 

 plete and satisfactory classification of the deposits for the 

 whole of that region is now capable of being made out. This 

 is particularly the case with those strata known to be of Car- 

 boniferous age. 



In the southern part of the region, in Arkansas, little com- 

 parison was made with the sections of other regions, and con- 

 sequently an entirely distinct grouping of the beds was 

 adopted, one that was only in a very general way comparable 

 to that in the north. Although much work had been done in 

 the state mentioned, no satisfactory parallelism of the forma- 

 tions of the two districts was brought out. Within the j^ast 

 two years, however, direct comparisons have shown clearly 

 that the geological sections of the Carboniferous formations of 

 the entire Ozark region are essentially the same. The impor- 

 tance of this determination over so large a region is obvious. 



The formations, which may be regarded as typically devel- 

 oped in Missouri, are fully described in the recent reports of 

 the Missouri geological survey, and while no further reference 

 need be made to them in this place they will be tabulated later. 

 As already intimated, there has been in Arkansas an entirely 



