about one fifth of a mile, by
inference from the depth of the Gulf of Mexico.' In the vicinity of New
Orleans, boring to a depth of two hundred feet, fossils, such as shells,
bones, etc., have been found. And at thirty feet specimens of pottery
and other evidences of Indian habitation have been discovered. The
foundation upon which rest the alluvial formations has been found to
consist of a hard blue silicious clay, closely resembling that met with
in the bed of the Mississippi. The most recent of the alluvial fields of
the Delta have been constituted a parish, termed Plaquemine. In 1800,
according to one authority, there were but very few acres in cultivation
in the entire parish. Since leveeing above, the deposit has been
extremely rapid, until now we find some excellent plantations in
Plaquemine. Fifty miles below New Orleans the tillable land is nearly a
mile in width; below there, it becomes gradually less, until it is lost
in the Gulf. Still the accumulations are going on, and it is impossible
even to surmise what changes the great river may yet effect in the
future geography of this section of the American continent.

Considering the multitude of streams and vastness of area drained by the
Mississippi, it is natural to suppose the river is much affected in the
stage of its water by the seasons. We have seen that the meltings of the
Rocky Mountain snows, the mountain rills of the Alleghanies, the waters
of the valleys of the upper river, of the Missouri, of the Ohio, the
Arkansas, the Yazoo, and the Red, all find outlet through this one
stream. There are certain seasons in the year when all these widely
distant localities are subject to a gradual approach of warmth from the
south, until they arrive at a sort of climatic average. This creates a
maximum of the supply of water. The inverse then takes place, and a
minimum results. For instance, in the latter part of December, the lower
latitudes of the Mississippi begin to experience their annual rains.
These by degrees tend northward as the season advances. In March
commence the thaws of the southern borders of the zone of snow and ice;
and during April, May, and June, it reaches to the most distant
tributary fountain head. The river now is at its highest. The reverse
then sets in. All the tributaries have their excess, the heats of summer
are at hand, drought and evaporation soon exhaust the surplus of the
streams, and the river is at its lowest.

To meet the great