Earth Facts
The distance from the surface of the earth to its center is estimated to be 20,926,202 feet; or about 3,963, miles; and the distance from the poles to the center of the earth is 20,854,895 feet, or about 3,951 miles. One degree of latitude at the equator is about 68.7 miles, and at the poles about 69-1/2 miles.
The circumference at the equator measures 24,902 statute miles.
The total area of the earth is 196,940,400 statute square miles, and its volume is 259,880 million cubic miles.
The land area of the earth covers 54,807,420 square miles.
The ocean, including the inland seas, covers 142,132,980 square miles, or about 72 per cent. of the total surface of the earth.
The Arctic Ocean, including Hudson Bay, contains 5,785,000 square miles; the Atlantic Ocean, 34,301,400 square miles; the Indian Ocean, 28,615,000 square miles; the Pacific Ocean, 67,699,630 square miles; and the Antarctic Ocean, 5,731,350 square miles.
The mean height of the land has been estimated at 2,440 feet, and the mean depth of the sea 11,470 feet. The highest mountain (Mt. Everest) is 29,000 feet high, and the greatest depth of the ocean is supposed to be 31,614 feet.
The North American continent has an area of 6,446,000 square miles, with exceeding 115,000,000 inhabitants, or a little less than 18 to the square mile.
The South American continent has an area of 6,837,000 square miles, with over 45,000,000 inhabitants, or about 6-1/2 per square mile.
Europe has an area of about 3,555,000 square miles, with a population of somewhat less than 400,000,000, or about 107 per square mile.
Africa has an area of 11,514,000 square miles, and a population of about 127,000,000, or 11 to the square mile.
Asia has an area of 14,710,000 square miles, with a population estimated at about 850,000,000, or a little less than 58 to the square mile.
Australia, New Zealand, and contingent islands, have an area of 3,288,000 square miles, with a population of exceeding 5,200,000, or about 27 to the square mile.
It is estimated that the surface of the earth is divided into somewhat more than 28,000,000 square miles of fertile soil, about 14,000,000 square miles of steppe, a little more than 4,000,000 square miles of desert, with the polar regions occupying nearly 5,000,000 square miles of land, most of which is covered with ice.
At the time of Emperor Augustus, there were said to be between 54,000,000 and 55,000,000 people upon the earth, but as the earth undoubtedly supported millions of inhabitants unknown to civilization, these figures are of little consequence.
The greatest measured depth of the Atlantic Ocean is a little over 27,000 feet; a depth of 30,000 feet has been found in the Pacific Ocean; 18,582 feet in the Indian Ocean; and 25,200 feet in the Southern Ocean. Soundings in the Arctic Ocean have failed to find a depth exceeding 9,000 feet.
Earthquakes.—The earthquake is caused, undoubtedly, by the cooling of the earth. The interior of the earth is a molten mass of fire and is slowly cooling. As it cools, it contracts, and if the contraction is near the surface of the earth, the surface is rocked and crevices may open, doing considerable damage, although most earthquakes cause but slight shocks and injure no one. Earthquakes appear principally in or near the tropics, but are occasionally felt all over the temperature zones. Earthquakes appear to have belts, and there is little to be feared from them outside of these territories.