380 Geographical Notices. 
“A remarkable feature in regard to this change of slope which occurs 
in the neighborhood of the course of the Niobrara is the shortness of its 
tributaries, the surface drainage seeming to be away from and not towards 
its banks, A result of this is the absence of the amphitheatre-like valley 
which rivers generally have, and which enable us to look down at the 
yards, only here and there a glimpse of the river below, so much isit 
cut its way entirely through the tertiary formation, flows along the ot 
ceous, while the bed of the Niobrara is in the miocene tertiary, raids 
cene forming the bluffs. The bed of the Niobrara is also, in two 
of its upper course, from three hundred to five hundred 
bed of the Platte river at corres nding points at the ret ee flows the 
ar, to : try, 80 
ublished on a scale“of’ 1 to 3,000,000, including the count}, 
4 Vad 
of which Capt. Humphreys is director. In its construch®l | 
only the results of the Pacific R. R. Exploring Lepper my 
those of the Mexican Boundary Commission, betel Lewis and 
iyestigations, which are reliable, including those 
