Nine-tenths of the whole area is forest. The tree limit varies from nine thousand four hundred to nine thousand seven hundred feet. Few of the plateau localities are bare. Pine, poplar, balsam, cedar and spruce grow abundantly and many to large size. In the spring and geyser localities the trees are often covered by deposits and buried. Whole forests have been thus entombed. Petrified trees are common. Wild animals are wholly unmolested. Deer, elk, buffalo and bear may be seen and approached near enough to photograph. Trout abound in the waters throughout.
NATURAL BRIDGE OF VIRGINIA
The Natural Bridge of Virginia (one thousand five hundred feet above the sea) is a huge monolithic limestone arch, two hundred and fifteen feet high, one hundred feet wide, and ninety feet in span, crossing the ravine of the Cedar Creek. It seems to be a remnant of a great horizontal bed of limestone rock that entirely covered the gorge of the brook, which originally flowed through a subterranean tunnel. The rest of this roof has fallen in and been gradually washed or worn away. The bridge is finely situated in a beautiful amphitheater, surrounded by mountains, on land originally granted by George III. to Thomas Jefferson, who built a cabin here for the use of visitors. Among the names upon the smooth side of the archway is that of George Washington (west side, about twenty-five feet up), which was the highest of all until a student named Piper actually climbed from the bottom to the top of the arch in 1818.
The first white man to attempt an exploration [587] of the region was a trapper named Coulter, who in 1805 traversed a part of this district. His tales were disbelieved, but were confirmed thirty years later by the discoveries of Bridger. In 1870 the first official survey was made, and in 1871 Hayden’s famous expedition revealed the glories of the Yellowstone district.
Climate and Irrigation.—The United States, stretching over such a vast area and having such great tracts of mountain and plain, must necessarily present a great variety of climate. The mean annual temperature ranges from under forty degrees to seventy-five degrees. The isotherm of fifty-five degrees mean annual temperature crosses the center of the country from east to west, passing through St. Louis. The mean annual rainfall for the whole country is about thirty inches, but there is a great difference in this respect between different parts. The rainfall is most abundant on the northwest Pacific Coast, on the Gulf Coast, and on the higher mountain ranges. On the great plains it is only ten to twenty inches, and there are large desert stretches in the Rocky Mountain region with a rainfall of less than ten inches.
Irrigation.—As far as lack of rainfall is concerned in the so-called rainless regions of the United States, this has been notably offset by great works of irrigation that have been steadily going forward. Agriculture, horticulture and vitaculture are, therefore, no longer dependent on chance but science, as the National Irrigation Congress expresses it.
Modern irrigation in the United States began in 1750 with the watering of the gardens in the hills and deserts of the coast of California by the adventurous missionaries from Mexico. Irrigation by English-speaking people had its origin in Utah one hundred years later. There the Mormons, separated by one thousand miles of untrodden desert from all cultivated land, found in irrigation their only means of escape from starvation.
In 1870 there were twenty thousand acres under irrigation, followed by a rapid development of small ditches, until in 1880 there were one million acres irrigated. Today (1917) upward of fifty million acres are included in reclamation projects, and it is estimated that there are upward of four hundred and fifty million acres still awaiting the scientific use of water.
The diversity of methods used in irrigation in the United States is remarkable. Practically every system to be found in the world can be seen in some part of the arid west. This is due to the fact that many of the irrigators have come from distant parts of the world and each seeks to introduce on his farm customs and practices of his old environments. This is particularly noticeable in California, where the Chinese irrigate their truck gardens in Chinese fashion, and Italians, Spaniards and Mexicans imitate for a time at least the practices of their forefathers.