OF THE UPPER MISSOURI. 33 
About thirty miles above the mouth of Turtle river, the Cretaceous bed No. 4 is revealed 
in the channel of the Niobrara, and at the mouth of Turtle river it covers the country 
with the exception of here and there an isolated hill composed of Pliocene beds. Turtle 
hill, Medicine and Bijoux hills on the Missouri are outliers of this great recent formation. 
About forty miles above the mouth of the Niobrara, No. 3 Cretaceous rises above the 
water-level, and on the Missouri becomes 60 to 80 feet in thickness. 'The country along 
the Niobrara is for the most part exceedingly sterile. The surface is principally covered 
with the movable sandhills, which render travelling very difficult, and very little timber 
is seen except a few stunted pines along the banks of the little streams. The valley of the 
Niobrara from its mouth for a distance of 30 or 40 miles, has a tolerably fertile soil with 
some excellent timber; but above that point to its source near Fort Laramie, the country, 
though not destitute of vegetation, cannot, it seems to me, be considered otherwise than 
an uninhabitable desert, fit only for the wild animals of the prairie and the still wilder 
Indian. 
PART II. 
The rocks of Nebraska and Kansas, so far as they are known at the present time, are 
referrible to the following geological epochs: 
I. Granite, Stratified Azoic, and Eruptive Rocks. 
II. Lower Silurian (Potsdam Sandstone). 
III. Carboniferous. 
1V. Permian. 
V. Jurassic. 
VI. Cretaceous. 
VII. Tertiary. 
VII. Post Pliocene or Quaternary. 
OnRAPTEAR Vii. 
I. GRANITE, STRATIFIED, AZOIC, AND Eruptive Rocks. 
In ascending the Missouri river, we meet with no indications of those disturbing in- 
fluences which have wrought such changes in the physical features of the country in the 
VOL. XII.—o 
