238 The American Geologist October, 1905 
present depth. In the Champlain epoch they refilled them 
or were so filled with water that they deposited debris far 
out on the adjoining mesa lands. Since then stream action 
and deposition have been going on about as now. 
Bad Lands. 
The bad lands are along the Oligocene outcrops. They 
are typical "mauvaises terres," but of course are less exten- 
sive than those farther west. They are almost destitute of 
vegetation ; and are chiefly noted for their picturesqueness 
and for their being the home of the gray wolf and the co- 
yote. 
Buttes. 
The buttes are situated upon the Oligocene along the 
break line of the Loup Fork, the strip having a general east 
and west trend. The buttes are conical or rectangular and 
flat topped, depending upon the hardness of the cap rock; 
the latter usually have their longest axis parallel with the 
nearest stream. The rectangular buttes m the vicinity of 
the White Thunder day school and those in the Robinson 
bad lands are capped with flint. The Rattlesnake buttes 
are capped with quartzyte sandstone. The conical buttes 
are generally capped with the Daimonelix beds of the Ari- 
karee formation where they have not been removed by 
erosion. The buttes occupy the inter-stream spaces and 
range from 200 to 300 feet in hight. 
It would seem from the observations that the flint and 
quartzyte capped buttes represent ponded areas of Arikaree 
times ; the Daimonelix beds, sand dune and stream regions, 
the flint and quartzyte sandstone having been formed under 
water. This opinion is strengthened by the fact that the 
flint contains snail and turtle shells ; the Daimonelix beds 
and sand areas, the bones of land animals. This difference 
in the formation of the original surface has been a leading 
factor in determining the course and position of the 
streams. The inter-ponded spaces, though being the higher 
ground, were less hard and have yielded more readily to 
erosive action ; hence are now the valleys. 
Rattlesnake Butte. 
The Rattlesnake buttes were so named on account of 
