C. R. Keyes — Provincial Carboniferous Terranes. 305 



Art. XXXIII. — Time Values of Provincial Carboniferous 

 Terranes ; by Charles K. Keyes. 



There have recently* been discussed at length certain 

 remarkable features relating to the development of the Car- 

 boniferous rocks in the province of the Mississippi valley. 

 The enormous thickness of the Carboniferous of the region — 

 probably upwards of 25,000 feet — and the nicety with which 

 it is separable into serial and minor subdivisions tend to make 

 the general geological section of the Continental Interior basin 

 the standard one for America. 



Periods Northern Sectio 



C kl&h-omo.n 



Missourian 



DesMoines* 



Southern Section -^.^^ 



Jrfi&nsasMu 



i/T"*--- 



1000' 



2000' 



izoo' 



18,000' 



170O 



Fig. 1. — Relative Formational Development of the Carbon if erous. 



In describing the various peculiarities of the formations only 

 the stratigraphical relations and features were considered. 

 The importance attached to the marked inequalities in the 

 development of the five series recognized which was made 

 such a prominent factor and the absence of all reference to the 

 relations of the several series to the time standard, appears to 

 have led to the inference that the time ratios were to be 

 regarded as approximately proportional. It was not the intent 

 to unduly emphasize the stratigraphical disparities at the 

 expense of the time representatives. The latter, for reasons 

 not necessary to specify in detail here, were simply thought to 

 be phases of the subject not to be considered in the article 

 mentioned. 



* Bull. Geol. Soc. America, vol. xii. 1901, pp. 173-196. 



