THE MISSOURI AND PLATTE RIVERS, ETC. 67 
portion of the Black Hills, and flows through the remarkable mam- 
malian cemetery or tertiary basin, draining an area of two hundred 
and fifty miles in length and fifty in breadth, Sraptiss into the Missouri 
in latitude 43° 41’. It has been partially explor 
s e Teton, or Bad river of the Sioux, an inferior sub-system, 
rises in the eastern portion of the Bad Lands, drains an area of one hun- 
dred miles in length and thirty in breadth, flows through the sterile 
clays of the cretaceous formation, and empties into the Missouri four 
miles below Fort Pierre, near latitude 44°. 23’ 28". 
5. The sub-system of the Shyenne, a river 0 it considerable size, takes 
; ome through the northern portion of the same spur and empties — 
into the Missouri near latitude 444°. This river drains an area of 
about three hundred and fifty miles in length and sixty to eighty in 
breadth, and flows for the most part through the sterile clays of the 
cretaceous formation. It has been partially PE 
6. Passing over the Moreau, Grand, an nd Cannon Ball rivers, which 
take their rise in the prairie near the eastern adie of the Black Hills, - 
and are less important streams, we come to the sub-systems of the 
Little Missouri, which rises in the eastern portion of the Black Hills, 
flows through the great Lignite Tertiary basin, draining an area 0 
about two hundred and fifty miles in length and fifty in breadth, and 
apie into the Missouri near latitude 474°. As jet it is very little 
ae latitude 48°, the Missouri bifurcates the right fork or Yellow- 
stone, draining an immense region, to the south and west, of which very , 
little is known ; and the left fork of the Missouri, oa Og the country 
further west and north near the base of the moun ains. The left fork 
of the Missouri contains a less volume of water = has a far less rapid 
current than the Yellowstone. 
On the left side I will only mention the two yubsayatelns of the 
James and Big Sioux rivers, which have been quite thoroughly ex- 
death by Nicollet and others, and drain a much more fertile aon 
than those before mentioned. 
The above gives a brief pale ae outline of the basin drained 
by the Missouri system of w 
Geologically the Missouri >a ir from the mouth of the Platte to 
he Rocky mountains, may be characterized by three principal divisions, 
represeneing three geological safer 
1. The Carboniferous system, the upper members of which are very 
well dercione at the mouth of the Platte, and extend to a point about 
thirty miles above Bellevue, Nebraska. Here the limestone strata 
dip beneath the bed of the river and are succeeded by a bed of yellow- 
ish sandstone, the exact age of which is not known, but probably 
m. 
em, which is positively known to exist at the 
basis Pan eon 
ce tot — mon 
