PENNSYLVANIAN. 457 



Des Moines and Missourian, respectively, are used for the two divisions. In Kansas these terms 

 have not been used, although essentially the same division is recognized. The basis of the divi- 

 sion is largely lithologic and economic. The Coal Measures in this field belong to one series 

 and represent a continuous sequence of deposition. The faunal change at the dividing line is 

 slight, but the division is none the less valid and important. The Lower Coal Measures include 

 the bulk of the productive coal beds throughout the field. From 93 to 98 per cent of the coal 

 mined comes from them. , These beds are relatively thick, are notably irregular, and show a 

 patchy distribution. They are associated with thick sandstones, thick bodies of shale, par- 

 ticularly of bituminous and argillaceous types, and with thin and unimportant limestones. 

 The Upper Coal Measures include a few very thin beds of coal of great regularity and extent. 

 They are associated with little sandstone, and with shale usually calcareous or argillaceous 

 in type. The measures also include a notable number of thick and persistent limestones. As 

 already stated, these differences are not pronounced to the south, though even here the general 

 relations are as stated above. The dividing line is drawn at the base of an important limestone, 

 40 to 80 feet thick, known variously as the Winterset, Bethany, or Erie. The general equiva- 

 lence of these three terms is well recognized, though there is as yet some doubt as to the exact 

 correlation of this and other minor divisions." Subdivisions of both the Upper and Lower Coal 

 Measures have been systematically recognized and mapped in Kansas by Haworth and his 

 associates. * In Missouri corresponding divisions have been recognized and partially mapped by 

 Keyes" and Marbut."* In Iowa divisions of the Lower Coal Measures have been recognized' 

 but have not been mapped except in Appanoose County, f 



"The divisions recognized in each State and their approximate correlation are shown in 

 the following table. Keyes has suggested more exact nomenclature and correlation." His 

 suggestions have not as yet been followed in mapping. 



Divisions of the Lower Coal Measures. 



"It will be seen that the Lower or Productive Coal Measures are made up of three divisions. 

 The uppermost, the Pleasanton shales, including the Altamont hmestones, attain a thickness 

 in Kansas of 200 feet. To the north they thin, until in central Iowa they are hardly to be sepa- 

 rated from the next lower member. In Kansas they have been grouped with this middle division 

 by Haworth under the name Marmaton formation. ^ The middle member passes under various 

 names in different parts of the field. In Kansas it includes the Pawnee and Fort Scott hme- 

 stones, with the intercalated Labette shales, and has an approximate thickness of 150 feet, a 

 thickness which it maintains well to the north. In southwestern Missouri the shale member 

 of the sequence is unimportant, and the hmestones, the Henrietta formation of Keyes,'^ form a 

 single escarpment, which may be seen near Hume, in Bates County. In northern Missouri 

 and southern Iowa the formation includes a number of thin limestones separated by shales and 

 carrjdng thin coal seams. This is the phase of the formation which has been called the Appa- 



a Haworth, E., Kansas Univ. Geol. Survey, vol. 3, pp. 101-102. 

 6 Kansas Univ. Geol. Survey, vols. 1 and 3. 

 <: Bull. Geol. Soc. America, vol. 12, pp. 173-196. 



i Missouri Geol. Survey, vol. 12, Clinton, Calhoun, Lexington, Richmond, and Huntsville sheets. 

 « Iowa Geol. Survey, vol. 5, pp. 374-398; vol. 6; vol. 8, p. 82. 

 / Iowa Geol. Survey, vol. 5. 

 . g Haworth, E., Kansas Univ. Geol. Survey, vol. 3, pt. 6, 1898. 

 ft Bull. Geol. Soc. America, vol. 12, 1901, p. 176. 



