578 Jel, Jay Jee ANID) Al. (Gs, SESROUNLAIRIO) 
the Iowa and Missouri surveys the beds formerly referred to the 
Middle Coal Measures have been considered to form a subordi- 
nate division of the Des Moines. In Kansas, Haworth has 
recognized a series of formations of which he correlates the low- 
ermost, the Cherokee shales, with the Des Moines... Above the 
Cherokee shales and below the Erie limestone, which is at least 
in a general way equivalent to the Bethany limestone, are placed 
the Oswego and Pawnee limestones, which with the interbedded 
shales, would seem to be the equivalents of the Middle Coal 
Measures of the older classification.' Since the earlier work 
there has been less attempt to build up general sections of the 
Coal Measures of this field and the tendency has been rather to 
emphasize the diversity of the beds and the lack of continuity 
of the strata. 
Non-persistence of individual strata is more or less charac- 
teristic of all shore formations. It is exceedingly difficult to 
conceive shore conditions under which beds could be deposited 
without this being true. When in addition it is remembered 
that there is excellent evidence that the particular shore line 
along which the lower Coal Measures of this field were laid down 
was unstable and subject to change through a considerable ver- 
tical range, it will be seen that the attempt to define subordinate 
formations in the Coal Measures cannot well be expected to 
yield satisfactory results. All the minor groups which are 
recognized may be expected to prove of local importance only. 
The beds of the upper portion of the Coal Measures, however, 
beginning with the base of the Missourian formation, indicate 
that they were found under radically different conditions. Indi- 
vidual bands of limestone, ten feet and less in thickness, may be 
traced step by step for one hundred or two hundred miles.2 
Bands of black shale, the ‘‘slate”’ of the miners, a foot or less 
in thickness, seams of impure coal measured in inches only, and 
thin ledges of impure black limestone of the type elsewhere 
t Univ. Geol. Surv. Kansas, Vol. I, p. 150, 1896. 
2 Bethany Limestone at Bethany, Mo., H. Foster Bain; Am. Jour. Sci., (4), Vol. 
V, pp- 433-439, 1898. 
