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The Territory of Arizona comprises the extreme south-western portion of the United States. It is bounded on the north by Nevada and Utah, on the east by New Mexico, on the south by Sonora, on the west by California and Nevada. It extends from the one hundred and ninth meridian west to the Great Colorado; and from 31° 28' of north latitude to the thirty-seventh parallel, and contains an area of about 114,000 square miles. The physical features of the Territory may be described as a series of elevated plateau, having an altitude of from 100 feet in the south-west, up to 6,000 and 7,000 feet above the sea level, in the north. Mountain ranges, having a general direction of north-west by south-east, extend over this lofty plateau the entire length of the Territory. These mountains often present the appearance of broken and detached spurs, and sometimes occur in regular and continuous ranges. Narrow valleys and wide, open plains lie between the mountains, while deep canyons and gorges, formed by the rains and floods, which sometimes rush with irresistible force from the mountain barriers, cross the country in every direction. The most extensive of these grand mesas, or table lands, is the Colorado plateau, in the northern portion of the Territory, occupying nearly two-fifths of its entire area. This great plateau has an average altitude of between 5,000 and 6,000 feet. Its surface is diversified by lofty peaks and isolated ranges; it is covered nearly its entire extent with fine grasses; it is penetrated on the west by the Rio Colorado, which has worn a channel thousands of feet in depth. It is also cut by the San Juan on the north-east, and the Little Colorado, the Verde, the Salinas, and the San Francisco on the south. These rivers form in places deep gorges, and again widen into beautiful and productive valleys. Perhaps

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nowhere on the continent can be found a more striking panorama of mountain, valley, mesa, and canyon. From north to south, from east to west, the country is crossed by mountain ranges and isolated peaks of strange and fantastic shapes. In the eastern portion of the Territory, extending from the San Francisco Mountain on the north, to the Gila river on the south, a long line of extinct volcanoes can be traced, and immense lava fields, which are found in different portions of the Territory, prove conclusively that Arizona was, in ages past, the scene of active eruptive agencies.

The south-western portion of the Territory may be described as composed of wide plains, covered in places with a sparse growth of grass, and dotted with peaks and detached spurs. The south-eastern portion of Arizona is made up of mountain ranges, which sometimes rise into commanding peaks, like the Santa Ritas and Mount Turnbull, with grassy plains and rich valleys lying between. The central portion of the Territory can show some of the most attractive scenery on the continent. It is also well watered, and contains the largest body of agricultural land in Arizona—the valleys of the Gila and Salt rivers. One of the wonderful curiosities of the Territory is the Grand canyon of the Colorado. This is one of the most stupendous chasms to be found on the continent, and probably has not its equal on the globe. It is a tremendous gorge, 400 miles in length, and from 1,500 to 6,000 feet in depth, cut through the eruptive rock by the river, in its passage for ages from its mountain sources to the sea. Down in the gloomy recesses of this forbidding gorge, which calls to mind the portal to Dante's Inferno, the light of day hardly ever penetrates, and the river, looking like a slender silver thread, foams and whirls among the rocks and falls which impede its progress. The canyon was first discovered by Coronado's expedition in 1540, and its length and depth accurately measured. It has been explored its entire length by Major Powell, who has given a most interesting and vivid description of its many wonders. The Little Colorado, one of the main tributaries of the great river, has also a canyon system of its own, but on a much smaller scale than the larger river.

The geological character of the Territory exhibits almost every formation to be found on the continent. North of the Grand Colorado and the Colorado Chiquito, the surface rock is a pure sandstone. The main ranges through the central portion of the Territory are composed of granite, porphyry, and slates. The mountains extending south-east from the great cone of the San Francisco to the thirty-fourth parallel, are mostly of volcanic origin. Between the Gila and the Sonora line is found granite, limestone, porphyry, trap, and much metamorphic rock. The lower portion of the Great Colorado basin bears traces of violent volcanic disturbance, and is covered in places with scoria and ashes; its upper portion is composed of granites, porphyry, and slates, with here and there isolated ranges and jagged peaks scorched and riven by the fiery flood which has swept over this part of Arizona in ages when our earth was young.

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Arizona is a land of marvels for the scientist and the sight-seer. Nowhere on the globe can the operations of nature be traced more clearly and distinctly. Torn and riven by stupendous gorges and deep canyons, crowned by lofty mountains, and diversified by immense plains, grassy parks, beautiful valleys, and elevated mesas, the topography of the country in variety, weird beauty, and massive grandeur, is not excelled on the continent. That the great plateau of Arizona was once an inland sea, there can be little doubt; and the isolated mountain masses, rising like islands above its surface, and the fantastically castellated buttes, which dot its immense plains, show clearly the erosion caused by the retreating waters. Arizona is a land that offers to the geologist and mineralogist a field both interesting and instructive; a land where the great book of nature lies open, with the record of countless ages stamped on its broad pages.


© Arizona Board of Regents