32 ON THE GEOLOGY AND NATURAL HISTORY 
The above section was taken some distance from the river, and the slope prevented me 
from continuing the section through the Titanotherium bed to the Cretaceous strata which 
_ are exposed in the channel of the river. 
October 10th. Leaving the valley of White river we proceeded in nearly a southeast 
course, ascending gradually to the dividing ridge between White and Niobrara rivers, 
where we find the largest development of bed D, which exhibits its usual lithological 
characters, but contains very few fossils. This bed has been eroded so that the surface of 
the country occupied by it is covered with conical hills, which are often capped with a 
considerable thickness of loose material, sand or marl. A similar configuration of the 
surface forms the basis of the sandhills, and the wind accumulates the loose sand around 
the summits of the hills. 
October 11th. Leaving Wounded Knee creek we begin to meet with indications of the 
Pliocene beds, which are so well developed on Loup Fork, Platte, and Niobrara rivers. A 
conical hill, left after the erosion of the surface around, reveals 42 feet of light gray and 
greenish gray fine calcareous grit, containing numerous fragments of shells and turtles, 
bones and teeth of Hipparion, &c. As we approach the Niobrara we firid that not only 
the valley of the river but the whole country is covered with the Pliocene formation ; and 
when the different strata are eroded, either in the channel of the streams or on the hills, 
bones and teeth of extinct mammalia and turtles are found. A section of the Pliocene 
beds from a vertical cut in the channel of one of the tributaries of the Niobrara presented 
the following series of strata: 
Dark gray or brown, loose, incoherent sand, contains remains of Mastodon and Elephant. 
A bed of sand gravel with pebbles. 
A yellowish white calcareous grit with many concretions. 
Gray grit with a greenish tinge. In this stratum most of the fossils are found. 
Deep yellowish red arenaceous marl. 
Sv = yo 
: Yellowish gray calcareous grit with many concretions in layers two to six inches in thickness. Aggregate 
thickness 60 to 100 feet. 
October 14th. Descended the Niobrara twenty-five miles. Sandhills cover the 
surface of the country a little distance from the river, and high vertical bluffs of Pliocene 
strata are revealed along the river. The banks of the river as well as those of its tribu- 
taries are very steep and high, and close together, forming deep caiions. Where the river 
has cut through the Pliocene bed numerous fossils were obtained. Upper Miocene bed 
D of the vertical section is not unfrequently revealed in the channel of the Niobrara, pre- 
senting a very irregular outline, showing most conclusively the great erosion that must 
have taken place prior to the deposition of the Pliocene beds. The irregularity in the 
surface of the Miocene bed D will be more clearly understood by the illustrated section. 
