14 University of Kansas Geological Survey. 
beds were formed, the individual gravels in which frequently have a 
diameter as great as four or five inches, requiring a great velocity 
of water to transport them throughout the distance they have been 
carried. Above and below such gravel beds the material is fre- 
quently composed almost entirely of the finest sand, and clay, and 
silt, which strongly implies that the movement of the water at that 
time was not rapid, but rather that it was slow and sluggish. 
AS is shown later in an article on the physical properties of the 
Tertiary these heavy gravel beds and the beds of fine sand and clay 
alternate with each other showing conclusively that there have been 
recurrences of conditions, a rapid movement of the water being 
followed by a slow one, which in turn was followed by another period 
of greater velocities. It therefore seems that the terrestrial move- 
ments were such, either in the mountains or the eastern part of 
the plains area, that the velocities of the mountain streams were 
changing alternately from slow to rapid, and again from rapid to 
slow and sluggish. Evidence on this subject is reached outside of 
the great plains area, as has been shown by various authors in de- 
scribing the drainage and general geologic conditions of the great 
west. It is well established that the main mountainous area had a 
eradual elevation rather than a rapid one; gradual upon the average 
but one irregular in character, with different periods of rapid eleva- 
tion intervening between long periods of slow upraising, or possible 
entire cessation in upward movements. 
It is somewhat difficult to decide the exact geologic date of the 
accumulation of the Tertiary materials in Kansas. From paleonto- 
logic evidence it would seem that the oldest Tertiary horizon in the 
state belongs to a later Miocene period. Similar evidence gathered 
from the paleontologic history of the great plains to the north in 
the Dakotas shows that Tertiary material began accumulating there 
considerably earlier, in the Oligocene, or possibly in the latter part 
of the Eocene. We have corroborative evidence of this in Kansas. 
The upper surface of the Cretaceous has been gradually eroded and 
subsequently covered with Tertiary material. It appears that after 
the elevation of the mountainous area sufficiently to produce dry 
land through the western part of the state, and probably over the 
whole plains area, a sufficient time elapsed before the deposition of 
