2() THE KANSAS CITY BRIDGE.

the river ; but its greatness is also shown by the character of the water, filled
with a light sand brought from the disintegrating rocks among the mountains,
by the strange geological mixture found in the gravel and pebbles below its
bed, and by the annual summer floods which come in their greatest violence
when other rivers are on the decline.

The chief tributaries of the Missouri are the Yellowstone, the Platte, the
Kaw or Kansas, and the Osage—the two latter being prairie streams of irregular
supply, and the two former, like the upper river, deriving most of their water
from the mountains, Hach of these rivers has its own characteristics and pro-
duces its distinctive freshets. The Yellowstone unites with the upper river to
cause the summer flood ; the Platte usually pours out its water+a little earlier in
the spring ; while the freshets of the Kaw and the Osage are of less regular
occurrence, and dependent largely on local rains. A combination of these freshets,
the waters from the melting snows among the mountains being supplemented
by heavy rains in the lower countries, has produced the great floods which
occur at long but irregular intervals, the last of which took place in 1844.
This flood, the only great flood of which we have accurate information, sub-
merged the entire bottom land below the mouth of the Kaw, and has been re-
garded by the settlers as an event too terrible to occur a second time ; but Indian
traditions mention other floods of similar character, one of which, occurring
towards the end of the eighteenth century, probably in 1785, is said to have con-
siderably exceeded that of 1844.

In many matters of topography the Missouri resembles the Upper Missis-
sippi, while it is substantially identical in these respects with the lower river.
Its course lies through a low alluvial deposit of bottom land enclosed on each
side by bluffs. The distance between these bluffs varies from a mile and a half
to 15 miles or more, the bluffs being generally highest, most rugged, and con-
taining the greatest quantity of rock, when they approach most nearly together.
For about 500 miles from the mouth of the river, or nearly to the southern
boundary of the State of Nebraska, the bottom land, except where artificially
cleared or where its width is very great, is covered with a heavy growth of
timber, the cotton-wood being the most common tree, while the sycamore,
black walnut, and several varieties of oak and elm also abound; farther north