Nature and Culture

by Harvey Rice

The elementary substances which compose the earth and its atmosphere are essentially the same, and are not numerous, so far as ascertained. The leading vital principle is oxygen, which constitutes at least one half of all known matter. The earth's crust is estimated to be about fifty miles thick. This estimate is based on the fact that in penetrating the earth, the heat uniformly increases at a rate which would fuse all mineral substances at that depth.

Hence, the interior of the earth is believed to be a region of molten substances, fiery billows that roll impatient of restraint, and escape here and there in the form of volcanic eruptions. Volcanoes are, therefore, but the outposts of gigantic central forces, and earthquakes but the spasmodic trials of their strength. It would seem, go where we will, that "fiery billows" literally roll beneath our feet. What Nature's ultimate designs are, it is impossible to predict. But it is pretty certain that her internal fires are working out some mystical problem. A scientific German has recently ascertained that the surface of the earth is gradually becoming hotter, and that in five hundred millions of years it will attain to such a degree of heat as to destroy human life. And yet there are other scientists equally wise, perhaps, who assert that the earth's crust is gradually cooling and contracting, and therefore radiating less heat, the final result of which will be the destruction of all life and a return of the glacial period.

Geological science, as well as revelation, impresses us with the belief that in the beginning "the earth was without form, and void,"—a chaos of atoms which were gathered, comet-like, from infinite space, and made to revolve in a globular mass by physical forces, until it became, by the condensation of its vapory atmosphere, submerged in a flood of dark and interminable waters. In consequence of the action of the waters on mineral substances, vast deposits of sediment accumulated, which, with the aid of pressure and chemical heat, gradually hardened into rocks, strata upon strata, like solid masonry, and varying in thickness from the fraction of a mile to thirty miles or more. Nature seems to have adopted this method of construction as a prerequisite to the severance of the land from the waters. In effecting this object, the explosive forces, long confined in the earth's interior, are supposed to have burst asunder the walls of their prison-house, suddenly upheaving continents and mountains from the depths of a dismal and shoreless ocean. It was then that the "dry land" made its first appearance, and was baptized in the pure sunlight of heaven.

The virgin soil of the earth, when thus exposed to the genial influence of the sun, soon produced vegetal life, and vegetal life animal life,—the one the food of the other. Thus Nature ever provides for her guests in advance of their reception. Yet in her formative processes she "makes haste slowly," though she may sometimes leap to conclusions. Her work never ceases. A million of years is to her as one day, and one day as a million of years. Hence everything has its age, and is lost in the ages. Of this fact we have reliable evidence in the strata of the rocks, and in the limited field of our own observation. There can be no doubt the earth has been many times baptized in fire and water, and its crust broken into fragments and thrown into strange angles and relations. These grand upheavals have occurred at dates vastly remote from each other, and are recognized by science as great geological periods.

The Ages of Nature, so far as relates to the earth, may be classed briefly as: the primary, or reign of fishes; the secondary, or reign of reptiles; the tertiary, or reign of mammals; and the modern, or reign of man. Each of these ages constitutes a grand chapter in the earth's history, which is easily read and understood by the masters of geological science. The same agencies which were employed in constructing the earth's crust are still employed in reconstructing it. In fact, the work of creation is still going on as in the beginning, if beginning there ever was in Nature's material processes. We see this illustrated in the changes which are produced on the earth's surface in our own time by the action of the rain, the wind, the frost, the flood, the glacier, the volcano, and the earthquake.

It is by these agencies that the hills and the mountains are graded down, and the detritus deposited in the valleys and in the sea; thus are valleys enriched and broadened, vast plains and deltas created, and continents enlarged. When the present hills and mountains have been reduced to plains, and the fertility of the soil exhausted, it is quite probable that another grand upheaval of the earth's foundations will occur,—the birth-power by which new hills and mountains are lifted up, and continents changed to ocean-beds, and ocean-beds to continents. It is these mighty changes and exchanges that prepare the way, and fit the earth for the production of higher orders of plants and animals, and perhaps a higher order of man.

In the course of unknown ages, Nature has enriched and extended the valley of the Nile hundreds of miles into the sea, by transporting thither the pulverized wealth of the Abyssinian mountains. Thus fertilized, Egypt has for many thousands of years sustained a dense population. Very justly has she been called not only the cradle of mankind, but the granary of the world. In like manner, the Ganges transports from the interior of India a sufficient amount of sediment annually to cover a township five miles square to the depth of ten feet, and by this means has extended the land hundreds of miles into the ocean. The Hoang-Ho, a river of China, by its deposits of alluvium in the sea has added an entire province to that country, comprising an area of ninety-six thousand square miles. Indeed, all rivers are tributaries to the sea, and all seas tributaries to the rivers. This exchange is effected mainly by the rains and the snows, the exhalations and the waterspouts. The clouds are but common carriers; this commerce is therefore a matter of mutual interest, and grows out of the positive necessities of sea and land. Though the elements appear to move in conflict, they really move in perfect harmony, and bring order out of seeming confusion.

In executing a gigantic work, no river has excelled the Mississippi. This "Father of Waters" has distinctly indicated in the record of his career the prehistorical age of the world, and the equally prehistorical advent of man. In his "march to the sea" he has left enduring landmarks, and with his battle-axe notched centuries long lost in the mighty past. The land which this majestic river has formed, by depositing sediment in the Gulf of Mexico, comprises an area of thirty thousand square miles. This deposit or delta has a depth exceeding one thousand feet; and the period required for its accumulation has been estimated by Mr. Lyell, the renowned geologist, at one hundred thousand years.

This estimate only embraces the deposits since the river ran in its present channel. The bluffs along the river rise in many places two hundred and fifty feet, and contain shells, with the remains of the mastodon, elephant, tapir, megalonyx, and other huge animals. It is evident that these bluffs must have belonged to an ancient plain or valley long anterior to the present level. In several sections of the valley as it now exists, excavations have been made deeper than the Gulf of Mexico, and successive growths of cypress-timber found, to the number of four or five distinct growths, the lowest lying at the depth of six hundred feet. Some of these trees are ten feet in diameter, and have from five to six thousand annual rings of growth.