83 KANSAS UNIVERSITY QUARTERLY. 
told. Within the borders of our own state, however, they are 
manifestly well defined in nature and will admit of closer mapping. 
The regional boundaries are here also the boundaries of geological 
formations. In discussing the physical features of Missouri, 
Marbut* has made the line of separation between the Carboniferous 
and the Sub-Carboniferous the western margin of the Ozark region, 
In Kansas the line follows Spring River, thus giving the region 
but a very small extent within the state in the extreme southeast 
corner. The western limit of the Prairie Plains is apparently the 
escarpment along the eastern border of the Permian formation. 
This is a very natural division, and a traveler passing westward 
cannot fail to notice the sudden rise in the elevation and the 
change in surface features. In the southern portion of the state 
the transition is marked by the Flint Hills. 
THE GEOLOGICAL STRUCTURE OF KANSAS. 
The geological structure of Kansas is best understood by refer- 
ence to a section extending in an east and west direction from the 
dome of the Ozark region to the Park mountains (see map p. 89). 
From this section it will be seen that within the Ozark Uplift is a 
core of archean rocks which are exposed within limited areas in 
southeastern Missouri. Around this core is an area of the older 
Paleozoic formations. Passing westward we find the beveled 
edges of the later Paleozoic formations. Along the line of the 
section they are represented as follows. First: undifferentiated 
Cambrian and Silurian and the Sub-Carboniferous. Within the 
Prairie Plains region lies the Carboniferous. The Arkansas Plateau 
region embraces the Permian, the Red Beds which are referred by 
some to the Permian and by others to the Triassic, the Comanche, 
Dakota, Benton and Niobrara, while resting unconformably upon 
these is an irregular deposit of the Tertiary. At the base of the 
Park mountains are the upturned edges of the Cretaceous and older 
rocks, while within the region the formations are much disturbed 
and the ranges contain eruptive and Archean elements. Kansas 
may be said to be an area of slight disturbance lying between two 
mountainous regions, whose complex histories have produced 
simple oscillations over the regions of the Prairie Plains and the 
Arkansas Plateaus. 
We cannot reconstruct with much certainty the original areas of 
these various formations, but they once extended much further to 
the east, and to produce their present surface and beveled out- 
*Physiographic Features of Missouri, Mo. Geol. Sur., Vol. 10. 
