Tne  MIDDEESCOALPSMEASURES OF THE WESTERN 
INGE RIORS COME ETE ED: 
THE most important coal field west of the Mississippi, so far 
as present development is concerned, is that which stretches 
from north central Iowa across portions of Missouri, Nebraska, 
Kansas, Arkansas, Indian Territory, and into Texas. In recent 
years there has been a good deal of geological work done within 
this field and some of the older conceptions of its stratigraphy 
are being changed. It is proposed to discuss here certain prob- 
lems relating especially to the northern end of the field; that 
portion extending from central Iowa to southwestern Kansas. 
The first extensive investigations of the geology of the lowa- 
Missouri coal field were those of Owen’ who traversed the main 
streams crossing the region and correctly outlined its limits. 
He determined the base of the Coal Measures and discovered 
many important facts with regard to structure and general geol- 
ogy, but made no attempts to build up a general section nor to 
divide the beds into minor formations. His successors, especi- 
ally Swallow, Broadhead, and White, applied themselves to this 
task. Swallow, in an introductory statement regarding the Coal 
Measures of Missouri,’ says that they appear to be separated 
into three divisions by two very important sandstones. ‘These 
three divisions he calls ‘‘Upper,” “Middle,” and ‘‘ Lower Coal 
Series.” With the change ‘‘series” to ‘‘measures” this termi- 
nology was generally followed by writers on this region up to 
1893 when Keyes, having previously noted the doubtful utility 
of the term Middle Coal Measures,3 suggested that the beds 
were better considered to form two formations which he named 
the Missouri and the Des Moines.* In the succeeding reports of 
‘Geol. Sury. Wisconsin, lowa, and Minnesota, 1852. 
? Geol. Surv. Missouri, I and II, p. 78, 1855. 
3 Bull. Geol. Soc. Amer., Vol. II, pp. 277-292, 1891. 
Iowa Geol. Surv., Vol. I, p. 85, 1893. 
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