Occasionally bodies fall upon the earth out of the sky. These are the meteors. They are not noticeable until they come within our air zone, when the friction between them and the air causes them to become red hot, often being entirely consumed by the heat before reaching the earth itself. They travel through the air zone at a speed ranging from ten to forty miles per second, accompanied by a heavy continuous roar, emphasized now and then by violent detonations. These meteors are solid bodies; containing a large percentage of iron and copper and single pieces have been found to weigh as much as seventy-five thousand pounds.
It is believed that these meteors are fragments which, ages ago, were shot out from now extinct volcanoes, with so great a velocity that they were thrown out beyond the attraction of the earth, and so becoming individual planets or heavenly bodies for the time being. Such being the case, they have traveled in independent orbits, until they at last encountered the earth at a point where her orbit crosses theirs. It may also be possible that these meteors were thrown from the planets or the stars, and as meteoric showers occur at intervals of thirty-three to thirty-four years, it is often believed that they are connected with comets and that therefore the comets, too, must be solid bodies like our earth. The number of meteors falling upon the earth adds continuously to the earth’s mass at a rate of about forty thousand tons per year.
Our earth is older than five hundred million years, according to Prof. Morean of Bourges Observatory, France, who holds that for half of that time, two hundred and fifty million years, some form of life has existed on its surface. Man, however, can boast of only some ten thousand years of ancestry in direct lines. In other words, in the life of this little globe he is, even in his most primitive form, a very recent arrival.
The earth was once a hot gaseous mass like the sun. Gradually the surface cooled, condensation took place forming the lakes and seas and after a great period of time vegetation appeared.
Water, entering the bowels of the earth, through cracks or some such opening in the surface, would evaporate into steam and under high pressure break through the earth crust and create a volcano, carrying with it great masses of molten rock. The hot geysers of Yellowstone Park, in America, are similar examples of such internal action.
In historic times there were lakes in the Sahara Desert and the so-called “Hopeless Desert” lying in the Rocky Mountains of North America, while in the Sierra Nevadas there was a time, not more than a million years ago, when all of the territory was well watered and vegetated. One of these lakes, in western Utah and extending over into Nevada, was one hundred and seventy-five miles wide, two hundred and fifty miles long and in places over a thousand feet in depth. Other evidences of this phenomenon, of tremendous masses of water entering into the bowels of the earth, are found particularly in the many caves among the Pyrenees and in the Mammoth Cave of Kentucky, the largest cavern in the world, in the upper galleries of which can still be seen the perforations through which the waters descended.
As we descend into the earth we observe an increase in temperature of one degree Fahrenheit for every fifty feet. At a depth of ten or twelve miles the earth is red hot. At a depth of a hundred miles the temperature is so great that if at the surface of the earth it would liquefy all solid matter.
Not only lakes and seas have disappeared, but whole continents, in much more peculiar ways. Where the Atlantic Ocean now lies, there was once, some four million years ago, a continent which we call “Atlantis,” connecting America with Africa, and believed to have been peopled with a race far more intelligent than any now existing upon the earth. They were one-eyed and had conquered the laws of nature; their airships flying by natural forces, such as do our sailboats. Their animals could speak and had great destructive powers. But this can be only hearsay, since now “Atlantis” lies at the bottom of the ocean, gone forever, like many mountains which have likewise gone down into the waters.
These surface changes, together with internal disturbances, created a wandering polar system and bodily displacement of both poles took place. With this came a great change in the climate of the earth. The lands of the present equator, which, only some twenty thousand years ago, were as cold as our present arctic zones, became tropical in climate, while the flourishing lands at the north and south poles grew desolate and cold, as they are today. The pole-axis of the earth has since changed considerably—Europe, only some twelve thousand years ago being covered with a great ice sheet.
The highest peak of the earth is Mount Everest, twenty-nine thousand feet above sea level, and the greatest depth of the sea is more than twenty-five thousand feet. Some of the earth’s surface lies below sea level, but it is not flooded on account of being surrounded by mountain ranges. A great part of the Sahara, for instance, is below sea level. The Sahara, less inhabited than any other area of the earth, covers one-twelfth part of the land surface of the earth, having an area of some four million square miles. It is by no means all sand; there are some plateaus and oases. In the days of Julius Caesar it was a fertile, well cultivated land, and was known as the “Granary of the Roman Empire.” With the fall of the old Roman Empire, however, the desert was neglected and the sands swallowed up the fertile lands.