34 
AMERICAN GEOLOGY. 
reaches St. Louis in about twenty-five days. But the most 
interesting fact which the Mississippian current reveals to us 
is contained in the sediment. The last resting place of this 
matter was in a cretaceous sea. Where they then came from, 
and how many transportations they had undergone, will never 
be revealed. In our geological reasoning they are destined to 
form the most modern deposits. They have undoubtedly passed 
through all the historical periods since aqueous deposits began 
to be formed. The particles are as old as the foundations of 
the earth, but the formations of which they are destined to form 
a part, are becoming the newest. They have been associated 
with the oldest organic beings, but they are now brought in 
contact with the most recent—with the people of the present 
age. The recent is made of particles derived from every known 
period. The water of the Mississippi is clear compared with 
the Missouri. Above its confluence with the latter it has a long 
and gentle descent. But its progress, in one respect, differs 
from that of the Missouri: it passes through many lakes, a fact 
which is unknown upon the course of the latter river. 
The Mississippian system, unlike the Atlantic system of drain¬ 
age, has two slopes, an eastern and western. The former, 
however, has more than twice the area of the latter. They 
unite, and form the basin of the Mississippi. 
Above New Orleans, where all the great trunks of this sys¬ 
tem of waters flow in one channel, the quantity of water is 
immense. According to the most reliable calculations relative 
to the quantity which this river discharges into the ocean annu¬ 
ally, it amounts to 14,883,360,636,880 cubic feet. The amount 
of sediment transported to the ocean by the Mississippi is 
28,188,083,892 cubic feet. This sediment is sufficient to form 
an annual deposit one mile square, and 1000 feet thick. As 
the delta of this river contains 13,000 square miles, and as the 
sediments of the delta are at least 1056 feet thick, it is evident 
that the time, required to accumulate so much material must 
have been greatly protracted. Fourteen thousand years has 
been stated as the result of the best observation which has hith- 
