Lozver Cretaceous of Kansas. — Gould. 1 1 
as composing the Lower, and the other four groups the 
Upper Cretaceous.* The Hne of separation between the Lower 
<ind Upper Cretaceous, or in other words, between the 
Comanche and Dakota has never been sharply marked. Both 
groups are noted for characteristic fossils — vertebrates, inver- 
tebrates and leaves in the Comanche ; and leaves, chiefly 
dicotyledenous, in the Dakota — but until recently very little 
work has been done in the way of correlation, nor has the 
Dakota itself been sharply defined. Mr. Logan says, "The 
Dakota formation may be subdivided, but there are no well 
defined separating lines. "t As Robert T. Hill once remarked, 
the Dakota seems to have been a sort of dumping ground for 
any leaf-bearing sandstone in the Cretaceous. 
The Dakota, however, has the advantage of having been 
studied along paleobotanical lines. There are few better 
known formations in the United States judged from the stand- 
point of fossils alone. By the efforts of such collectors as 
Hayden, West and Sternberg, and such paleobotanists as 
Heer, Capilini, Newberry, Lesquereux, Ward and Knowlton 
the scientific world has been introduced to a wealth of fossil 
flora perhaps the most perfect known. 
Most unfortunately, however, the collecting has been done 
in most cases by those who either could not or at least did 
not work out the stratigraphy and so a good part of the 
scientific knowledge has not been forthcoming. In some 
instances leaf-producing localities have been deliberately con- 
cealed and specimens collected fifteen miles or more from the 
locality indicated^ by the label. 
Our knowledge of the Comanche of Kansas is quite recent. 
Professor Cragin to whom we are indebted for the earliest 
as well as the most careful studies in these formations con- 
sidered these rocks as Dakota and Benton as late as 1889. 
Since that time, however, a number of papers have appeared 
most of which will be referred to in this article. As a result 
of these studies the Comanche is as familiar to the geologist 
as any other group in the state. 
There are in Kansas two principal regions in which the 
*See Geo. I. Adams' paper, University Geological Survey of Kansas, 
Vol. IV, pp. 15-27, 1898. 
tibid., Vol. II, p. 207, 1897. 
