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THE ARKANSAS COAL MEASURES.
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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 1 N., Range 28 W., Section 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 marianum 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 Arkansas," 1860, and in the Second Geological Survey of Pennsylvania, 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,"[1] throws much new light on the stratigraphic and regional distribution 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[2] published from Arkansas belong to the horizon of the Upper or Productive Coal Measures.

The Van Buren plant bed is thought, from paleobotanic evidence, 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 fossils. The Van Buren plant bed occurs below the Poteau mountain marine beds, and above those in Sebastian county, Township 8 N., Range 32 W., Section 12; and these latter marine beds occur above the horizon of the Ouita coal.

  1. ↑ An unpublished report of the Geological Survey of Arkansas.
  2. ↑ The work of the Survey shows that the plants described by Lesquereux from Washington county as Sub-Conglomerate belong to the Lower Carboniferous.
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