As the valley of the river from age to age grew in elevation by deposits of sediment, a new growth of cypress was produced, and is now supervened by the live-oak plain, so called, which has had an existence, as estimated by the annual rings of the oaks, of fourteen thousand years.
In excavating for gas-works at New Orleans, a human skull was found beneath the roots of a cypress belonging to the fourth-forest level, in a good state of preservation, while the other bones of the skeleton crumbled to dust on exposure to the air. The type of the cranium was that of the aboriginal American. Now, if we take the period required to form the live-oak level, and add it to the time required to produce the next three subterranean growths of cypress, which overlie the fourth growth, in which the cranium was found, it clearly proves that the human race existed in the great valley of the Mississippi more than fifty-seven thousand years ago.
Not only in the valley of the Mississippi have fossil remains of man and animals been discovered at depths and in formations that prove their remote antiquity, but in many other parts of the world. Not many years ago, a human skull was found in Brazil, embedded in a sandstone rock overgrown with lofty trees. There is still preserved, in the museum at Quebec, a human skull which was excavated from the solid schist-rock on which the citadel now stands. Human skeletons have also been found in the island of Guadeloupe, embedded in a rock said to be as hard as the finest statuary marble. Even so recently as the year 1868, while sinking a well at the Antelope station, on the Union Pacific Railroad, the workmen penetrated a rock six feet thick, and at eighty feet below the rock discovered a human skeleton in such a state of preservation as to be readily recognized as such.
In another instance it is said that a human skull was discovered in Calaveras County, Cal., at the bottom of a shaft which had been sunk one hundred and thirty feet below the surface. It was found deposited in a bed of gravel with other organic remains, and beneath the eighth distinct geological layer of earth and gravel, where it must have lain, according to the estimate of Professor Whitney, the geologist, for a period of at least one hundred thousand years. This remote antiquity of man is also confirmed by discoveries in every part of the world of the fossil remains of domestic animals as well as of man, including implements of human invention, such as flint arrow-heads, stone axes, war-weapons, cooking-utensils, in localities which preclude the idea of their belonging to an age that has a written history.
It is not unfrequent that fossil remains of human bones and of animals are found embedded in the coral-reef limestone of Florida. In fact, says Professor Agassiz, the whole peninsula of Florida has been formed by successive growths of coral reefs and shells; he estimates the formation of the southern half of the peninsula as occupying a period of one hundred and thirty-five thousand years. The sea contains ingredients which feed innumerable animalcula, especially the polypes, or coral-builders, which have the power of secreting calcareous matter. These myriads of noiseless architects are ever busy in building for themselves fairy temples in the depths of the ocean, of the most delicate and beautiful workmanship, and in erecting pyramids and islands, and in extending continents.
In the mean time there are other agencies of a very different character continually at work, modifying the earth's surface, and preparing it for sustaining a still higher order of vegetal and animal life. As a result of these agencies, especially the volcanic, it often happens that serious calamities befall the human family. In the course of a century, not less than two thousand volcanic eruptions occur on the globe, equal to twenty a year, or one every eighteen days. The whole number of volcanoes known to be active at the present time exceeds three hundred; and doubtless many times that number have long since become extinct.
In Europe, Asia, Africa, and America, there are extensive tracts or belts of country which are volcanic in their character; and especially is this true of the entire American-Pacific coast, and the ocean-bed adjoining it. Often have long lines of this coast been elevated or depressed many feet, as if the whole continent were afloat, and tossing like a ship on a stormy sea. Neither in the past, nor in the present, has the earth seemed to rest on a sure foundation. Even in apparent security there is no positive safety.
Nature must and will exercise her sterner as well as her milder powers. In achieving gigantic works, she employs gigantic powers. Her forces are her own; and when she directs them to execute her mandates, she is promptly obeyed. She models and remodels the earth's exterior and interior at pleasure, but never without a beneficent design. Earthquakes break up the earth's crust. Internal fires melt it. Exploding gases lift it. Gravitation moulds it. The atmosphere cools it. The sun and the rain clothe it with verdure; and flowers crown it with beauty. In this way the earth's surface seems to have been prepared for the advent of man, and its interior supplied with coal-fields and reservoirs of oil and gas for his use.
Though Nature has made for man ample provision, she requires him not only to help himself, but to take care of himself. Nor does she give him formal notice to keep out of harm's way when she wishes to break up the earth's crust and re-cast it, but proceeds at once. She may sink or elevate a continent at a blow, or she may do it by slow degrees.
The earliest writers give us accounts of terrific earthquakes. Thucydides alludes to volcanic eruptions which occurred five hundred years before the Christian era. In the vicinity of volcanic mountains, it has happened that city after city, in the course of ages, has been engulfed, one upon another, in molten lava, or cinders, leaving no record behind them of their unhappy fate. Herculaneum lies buried a hundred feet deep beneath the modern city of Portici; and beneath Herculaneum, a city still more ancient has been discovered, whose name and history are entirely unknown. How many other cities lie buried at the foot of the old fire-crowned monarch of Italy, no one can tell; but doubtless there are several of them. What induced people to occupy a locality so perilous, it is difficult to say, unless it was the superior fertility of a volcanic soil.