76 University of Kansas Geological Survey. 
On the Atchison, Topeka & Santa Fe railway running from Win- 
field to Medicine Lodge this series is first seen in the vicinity of 
Mayfield and Milan. So far as determined, the base of the Red-Beds 
rests conformably on the Wellington formation. The line of sepa- 
ration has been traced to some extent and indicated on the geo- 
logical map as crossing irregularly the western part of Sumner, 
eastern Kingman, western Sedgwick and eastern Reno counties, to 
the valley of the Arkansas river. The top of the series is determined 
on the west and north by either the base of the Comanche series 
or the Tertiary where the Comanche is wanting. The series has a 
thickness of perhaps 1200 feet, determined partly from well sec- 
tions and partly from surface exposures. 
In correlating this mass of rocks investigators have referred 
them to several systems and a brief review of such correlation may 
be of interest. | 
On the geological map of Kansas published by Professor Mudge 
in 1878,! the greater part of the area south of the Arkansas river, 
now known to belong to the Red Beds, is represented as of upper 
Carboniferous age though it is stated in the text that west of 
Harper the region has been little examined by himself or others 
“but appears to be represented by the Fort Benton and Dakota 
eroups.”* This does not agree with the map, for Barber, Comanche 
and the southeastern part of Clark county, to the west of Harper, 
are colored as belonging to the upper Carboniferous. 
The next paper of importance bearing upon this region is the 
“Sketch of the Geology of Kansas” by Professor St. John in 1883. 
On the “Geological map of Kansas®*”’ in this report, the line sepa- 
rating the Cretaceous and Upper Coal Measures south of the Ar- 
kansas river, is represented as crossing central Reno, eastern King- 
man and Harper counties. In the text of this report, the Dakota 
formation of the lower Cretaceous is fairly well described, and the 
Red Beds are provisionally correlated with it. Prof. St. John says 
“In the region south and west of the Arkansas, the deep-red sand- 
stones, presumably belonging to the same formation [Dakota], owing 
1 First Biennial Report State Board of Agriculture of Kansas, 2nd ed., p. 47. 
Albian soo: 
3 Third Biennial Report State Board Agriculture of Kansas, op. p. 575. 
