444 ELIOT BLACKWELDER 
2. About the close of that period the beds were moderately folded 
and locally faulted. 
3. During the resulting cycle of erosion, the arches and scarps 
were beveled off and a moderately low hilly surface was produced. 
4. Through terrestrial sedimentation in the Oligocene and Miocene 
epochs the Eocene surface was partially buried, although it probably 
remained exposed in the mountains. 
5. After this, probably in Pliocene times, much of the region was 
reduced to a peneplain on which some notable monadnocks remained 
standing. 
6. This was followed by rejuvenation, and the resulting cycle of 
erosion was long enough to permit the cutting of wide flat valleys in 
the arches and the excavation of the Laramie basin. 
7. The most recent episode is a later rejuvenation which has caused 
new canyons to be cut east of the Laramie divide but not as yet in 
the plain west of it. 
8. The region has not been glaciated, but its surface has been 
modified in detail and perhaps in gross by wind carving. 
