362 CHARLES R. KEYES 



the Carboniferous is well known. In Indian Territory the infor- 

 mation is not yet as full as would be desirable. Still there are 

 enough facts at hand to indicate the general features of the 

 main subdivisions, or series. The Missourian, or more strictly 

 marine series, composed of important limestones, does not 

 appear to extend down the Arkansas valley into Arkansas, nor 

 to change very much in lithological character. The Paw- 

 huski limestone in eastern Oklahoma, regarded by Smith 1 as 

 representing the same horizon of " Upper Coal Measures " farther 

 east, certainly cannot be stratigraphically equivalent to any 

 part of the Coal Measures that exist in the same latitude in 

 Indian Territory. While it is not yet known with certainty just 

 what its exact equivalent is, it is quite probable that it is the 

 southern extension of what is termed the Iola limestone in the 

 region to the north. If this is the case, the position of the 

 limestone exposed in the quarries at Pawhuski is very near the 

 base of the Missourian, or "Upper Coal Measures." 



If, as now appears probable, the enormously thick Coal 

 Measures of the Arkansas valley are practically the exact equiva- 

 lents of only the lower division, or the Des Moines series of the 

 region farther north, instead of representing the entire interval 

 between the Mississippian and the so-called Permian (Okla 

 homan),or that part of the Carboniferous above the Cottonwood 

 limestone in Kansas and Oklahoma, the explanation of the great 

 increase in the thickness southward, would seem still more diffi- 

 cult. There have been, however, a number of new facts recently 

 brought out regarding the diastatic changes that have taken 

 place in the Ozark region, and some of these have a direct bear- 

 ing upon the question under consideration. 



It has been lately shown 2 that during the Kaskaskia, or 

 closing epoch of early Carboniferous times in the Mississippi 

 valley, there was a series of rapid changes in the relations of 

 land and sea. At the beginning of the Kaskaskia the shore 

 line had moved southward 400 to 500 miles at least from the 



1 Proc. Amer. Philos. Soc, Vol. XXXV, p. 230, 1896. 



2 Bull. Geol. Soc. America, Vol. Ill, p. 296, 1892. 



