148 The Missouri River. — Broadhead. 
These facts do not favor the separation of the Paradoxides 
beds from the Lower Cambrian, or their erection into a sepa- 
rate division as Middle Cambrian. If there is to be a Middle 
Cambrian it would rather seem that the Olenus fauna holds 
this position. But as has been shown the faunal relationship 
of the Olenus beds to those which follow them forbids their 
separation, just as in the Lower Cambrian a similarity in the 
forms correspondingly connects the Olenellus with the Para- 
doxides fauna. 
THE MISSOURI RIVER. 
By G. C. Broadhead. 
There remain certain features pertaining to the physical geog- 
raph}'- and geology of the Missouri not fully understood. 
Such I will briefly discuss, chiefly from my own observations 
which have been taken at the head of the main stream, at the 
Three Forks, Benton and Bismark, and extended from Sioux 
City to the mouth, the lower part having been studied both 
by land and water. 
The valley drained by the Missouri may be divided into 
three areas which differ geologically and topographically, viz. : 
1st. The upper or mountain district ; 2nd. The plains : 3d. 
The lower valley region ; or 1st. The mountain and igneous or 
volcanic ; 2d. The plains, or Tertiary and Mesozoic ; 3d. The 
lower valley or Palteozic. 
The Missouri is formed by the junction of the Jefferson, 
Madison and Gallatin at Gallatin City, Montana, lat. 45*^ 52' 
N., long. 113° 30' W. of Greenwich. These three streams take 
their rise amid the snowy peaks of the Rocky mountains and 
for 400 miles below the forks the water is clear and beautiful. 
The latest revised estimates give 2,766 miles from the mouth 
to the Three Forks. Early trappers and voyageurs considered 
the Missouri as 4,000 miles long. The Three Forks are each 
from 200 to 300 miles long and bold and rapid. The Madison 
takes its rise in the southwest part of the Yellowstone park, 
being formed by the junction of the two forks of the Firehole 
river. The east fork is about ten miles long, the south fork 
about 25, traversing in its course the homes of the grandest 
geysers of the world and deriving its chief supply of water 
from them. The mountains adjacent are of later Tertiary 
volcanic. Just cast of this and but a few miles aAvay the Yel- 
