State University of Missouri.


Physical geology is the science which deals with the past changes of
the earth's crust, and the causes which have produced the present
geographical features, everywhere seen about us. The subject of the
present address must therefore be considered as one of geology rather
than of geography, and I propose to trace for you the early history of
the great Mississippi River, of which we have only a diminished remnant
of the mightiest river that ever flowed over any terrestrial continent.

By way of introduction, I wish you each to look at the map of our great
river, with its tributaries as we now see it, draining half of the
central portion of the continent, but which formerly drained, in
addition, at least two of our great lakes, and many of the great rivers
at the present time emptying into the colder Arctic Sea.

Let us go back, in time, to the genesis of our continent. There was once
a time in the history of the earth when all the rocks were in a molten
condition, and the waters of our great oceans in a state of vapor,
surrounding the fiery ball. Space is intensely cold. In course of time
the earth cooled off, and on the cold, solid crust geological agencies
began to work. It is now conceded by the most accomplished physicists
that the location of the great continents and seas was determined by
the original contraction and cooling of the earth's crust; though very
greatly modified by a long succession of changes, produced by the
agencies of "water, air, heat, and cold," through probably a hundred
million of years, until the original rock surface of the earth has been
worked over to a depth of thirty or forty miles.