Smith.] ^^^ [Oct. 2, 



paleontologic or stratioTapliic break, but merely on the oecurrence or 

 non-occurrence of coal. 



The divisions that are recognized in Pennsylvania could not be recog- 

 nized in Arkansas, but the strata of the two sections arc correlated as 

 far as possible, with the scanty data now at hand. 



The Lower Coal Measures. 



Of the age of the Lower Coal Measures we have only stratigraphic 

 evidence, their position above the limestones of the Lower Carboniferous 

 and below the coal-bearing beds of the L^pper Coal Measures being 

 unmistakable. But their known fauna and flora have been too limited 

 and indecisive to enable us to correlate the stages with those of other 

 Carboniferous areas, since collections have been made in but few places, 

 and these chiefly in sandstones, where the preservation of fossils is 

 usually unsatisfactory, and the determination uncertain. 



But the Lower Coal Measures correspond in a general waj- to the 

 Strawu and the lower part of the Canyon division of Texas, to the Potts- 

 ville Conglomerate series, the Lower Productive Coal Measures, and 

 part of the Lower Barren Coal Measures of Pennsylvania. The series 

 corresponds in the main to the Middle Carboniferous limestone of eastern 

 Eussia. 



The Ujyper Coal Measures. 



The Arkansas Upper Coal Measures corresj^ond to the upper part of 

 the Canyon and the whole of the Cisco division of Texas,* and below 

 the transitional Permo-Carboniferous or Artinsk stage, to which latter 

 age the lower part of the Wichita and Albany divisions of Texas 

 belong. The Lower Permo-Carboniferous beds of Kansas and Nebraska 

 iire also probably to be correlated with the Artinskf stage, although 

 AVaagen:}: classes the entire series with the ammonite-bearing beds of 

 northern Texas, described by Dr. C. A. White, in Bulletin 77 of the 

 U. S. Geological Smwey. Most of the latter Texas beds belong rather 

 above the Artinsk stage, and in the true Permian, and are probably of 

 the same age as the Middle and Upper Productus Limestone of the Salt 

 Eange. 



Waagen, in Salt Range Fossils, Geological Eesults, p. 238, gives a com- 

 parative table, showing the relationship of the upper Paleozoic strata 

 all over the world. While the position assigned some of the American 

 deposits does not agree with that accepted by most American geologists, 

 still the table is very useful for comparison, and it has been freely used 

 In compiling the comparative table accompanying this paper. 



*The writer, in Journal Geology, Vol. ii, p. 194, following Karpinsky, plaoed the Popa- 

 noceras parkcri bed.s iu the lower Permian or Artinsk, but in this he was mistaken. Prof. 

 W. F. Cummins told the writer that these beds arc not in the I'pper Cisco, but in the 

 Strawn division, and therefore are Lower Coal Measures. 



t Karpinsky, Anwionren der Artinsk- St life, p. '.'>'2. 



I Salt Range Fossils, flcological Results, p. 201. 



