THE A RKA NSA S COAL ME A S URES. 1 9 5 



The beds of Poteau mountain, Indian Territory, are probably 

 of the age of the Lo-ping strata of China, while the yellow shales 

 of Scott county, Arkansas, Township i N., Range 28 W., Sec- 

 tion 4, southeast quarter of southeast quarter, are probably of 

 the age of the Upper Carboniferous limestone of Moscow, and 

 the west slope of the Ural Mountains, if we can judge by the 

 occurrence of Gastrioceras mariammi and Pronorites in them. This 

 would make them older than the Poteau mountain shales, which 

 is very likely the case. 



Paleobotanic evidence. — Our knowledge of the paleobotany of 

 the Coal Measures of Arkansas has been up to the present time 

 very limited, depending almost entirely on the publications of 

 Lesquereux, in the "Second Annual Report of a Geological 

 Reconnaissance of the Middle and Southern Counties of Arkan- 

 sas," i860, and in the Second Geological Survey of Pennsyl- 

 vania, Report of Progress, P, "Description of the Coal Flora of 

 the Carboniferous Formation in Pennsylvania, and throughout 

 the United States," 1884. 



The joint monograph of H. L. Fairchild and David White, 

 on the "Fossil Flora of the Coal Measures of Arkansas,"' 

 throws much new light on the stratigraphic and regional dis- 

 tribution of species, and has been of material aid in correlating 

 the Arkansas strata with those of other regions. They prove 

 that all the Coal Measure plants - published from Arkansas 

 belong to the horizon of the Upper or Productive Coal Measures. 



The Van Buren plant bed is thought, from paleobotanic evi- 

 dence, to belong above the horizon from which most of the coal 

 of Arkansas is obtained, that of the Ouita coal, and this agrees 

 with the evidence given by the stratigraphy and the marine fos- 

 sils. The Van Buren plant bed occurs below the Poteau moun- 

 tain marine beds, and above those in Sebastian county. Town- 

 ship 8 N., Range 32 W., Section 12; and these latter marine 

 beds occur above the horizon of the Ouita coal. 



^ An unpublished report of the Geological Survey of Arkansas. 



^ The work of the Survey shows that the plants described by Lesquereux from 

 Washington county as Sub-Conglomerate belong to the Lower Carboniferous. 



