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PART FOURTH.

THE TWO SLOPES-WEST AND EAST OF THE VALLEY.

The Mississippi Valley has been spoken of as lying between two other regions whose resources, natural and industrial, are very different from those of the great central alluvial plain as well as from each other. They have each outside relations by their respective oceans, through commerce, that are scarcely less important to other sections of the country than to themselves.

The Valley is, first of all, agricultural. However great its manufacturing and mining may become, that industry must always take the lead from its geological structure, its great extent of fertile soil, its climatic conditions and its ready relations with populous Europe. The East, or Atlantic Slope, starting as a string of English colonies along the coast, devoted almost wholly to agriculture, soon developed commerce, and then manufactures, till it has become one of the centers of the world for those interests. The West, or Pacific Slope, so far as it is Anglo-Saxon-and its real development began with the advent of that race-is little more than one generation old. Its leading attraction has been mining, although agriculture has won singular triumphs in the fertile and better watered basins and valleys. Ultimately its commerce must develop to immense proportions, and manufacturing is likely, in the long future, to flourish to an extraordinary degree.

Notwithstanding the prominence that has been shown to belong to the Great Valley as the seat and center of a new and remarkable race, the Anglo-American and its model

Republic, it, still, contains but a part of that race and is only one of the sections of the republic. It gave a field, most rare and suitable, for the exercise and expansion of the peculiar qualities of the race after its basis of character and development had been acquired on the Atlantic Slope, and prepared it for a special and kindred form of growth on the Pacific Slope and the Great Mountain Plateau. Each of the sections has impressed, and is impressing, on its inhabitants special qualities varying in harmony with the Geological and Historical past. They unite in the most admirable and valuable way to constitute one country and nation. Each has become quickly prosperous and rich through its connection with the others. It would be difficult to say which has conferred the most and largest benefits on the others, if the Valley had not predetermined the question by its greater available surface, the variety of its colossal treasures, and the extreme readiness with which it surrenders them to the intelligent industry of the remarkable race that settled it.

This section can not be perfectly understood, nor can the extreme promise of its future be fully comprehended, without a tolerably full display of the character, resources, condition and relations of the two others. Some chapters, therefore, will be given to each of them.

CHAPTER I.

THE PACIFIC SLOPE-HOW IT WAS FORMED.

The mountainous regions of the West within the United States are about one thousand miles in width by not far from two thousand in length. There is first a high plateau with a general elevation of 5,000 feet above the level of the sea, though it varies in places between 4,000 and 7,000. On the east this elevation extends far into the Valley. From this great average hight of about one mile (5,280 feet) spring a series of lofty mountain ranges, the higher peaks of which rise about twice as much farther into the upper air, or from 12,000 to 15,000 feet above the sea level.

What produced such a vast elevation of a region so wide and extensive? A general answer will be found in the first chapter of Part First, where the forces adequate to such an immense result are discussed. These forces were connected with the cooling of the earth, the gradual thickening and contraction of the hard crust above a sea of liquid rock. So great a result as the Rocky Mountain plateau and its elevated ranges could not have been obtained in the earlier part of the earth's geological history, because the crust was then thinner, would give way more easily, and be less able to support itself, or find support, if raised so high. The masses which form mountains, and the rocks that rest against their sides, tell their comparative age with great clearness and certainty to a person who has learned to read the narrative they have to tell. It is one of the most positive and unmistakable among the many classes of facts they have been commissioned to reveal.

They do not, inaeed, speak in human language, and so do

not measure by years; yet they have a very accurate measure of their own which has only to be translated to give us a fair idea of what is geologically young and old. It is as yet difficult to express geological measures of time in figures with a certainty of being nearly exact; yet some very learned men, whose studies and conclusions have been received with great respect by those who are the best judges of their value, have called in astronomy to assist in the computations and have given us figures which are now finding general acceptance as at least approximations.

Sir William Thompson has estimated the time that has passed since the Life Force first began to produce vegetable and animal organisms, traces of whose remains are found in the early rocks, at one hundred millions of years. This is a period too long for us to realize, and yet it is some thousands of times shorter than some geologists claim.

The comparative length of the three great geological periods of time since life began on the earth has been estimated, by authorities of the highest reputation, as twelve for the Paleozoic-the Ancient or early period-three for the Mesozoic or Middle period-and one for the Cenozoic, or Recent period. This would give something over seventyfour millions of years for the Ancient Time; eighteen millions for the Middle Period; and six millions for the last Period reaching to the present. Some parts of the Green Mountains, of Vermont, and the low Laurentine range north of the St. Lawrence, in Canada, date back to about the beginning of the estimate or one hundred millions of years, if the above estimate be allowed. The Alleghanies were raised about the close of the Paleozoic, or Ancient Period, and so are nearly seventy-five millions of years younger; while the Rocky Mountains and the high plain on which they stand were raised some twenty or more millions of years later. The elevation commenced near the close of the Mesozoic, and was not fully completed till two-thirds or more of the Ceno

THE TIME REQUIRED FOR MOUNTAIN-MAKING.

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zoic had passed. The above estimate of one hundred millions of years is not considered by men of science as final; yet there are many strong reasons for believing it near the truth. Closer study may change the verdict, but the more careful the recent study has been the more have geologists been impressed with the idea that time is long, that nature has been infinitely deliberate in her work, and that vast periods must be allowed.

The raising of the Rocky Mountains was not all done at once, as to the plateau or the various chains of high peaks. The Sierra Nevada and the Wahsatch ranges are among the oldest-the ranges in Colorado and Montana, and the Coast ranges of California, Oregon and Washington being a later product of the elevating force, the time occupied from first to last being some millions of years. It will be remembered

that Cenozoic, or Recent Time, is divided into two great Periods, the Tertiary and Quaternary. The Tertiary is subdivided into the Eocene, Miocene and Pliocene Eras, and the Quaternary into the Glacial, Champlain and Terrace Eras. The permanent elevation of the Rocky Mountains commenced just before the beginning of the Tertiary and was about completed at its close. Small changes have been in progress down to the present, yet the Rocky Mountain region was, at the beginning of the great Ice Age (or the close of the Tertiary) substantially what it is now except the surface changes produced during that Era and later. Geologists do not attempt to determine the actual space of time which passed during the lapse of each of the periods and eras, but the six million years which Sir William Thompson's figures would assign to the Recent Period, or Cenozoic, would allow three to five millions to the Tertiary.

That is a very long period; but the elevation of the vast plateaus and mountain peaks of North and South America must have been almost inconceivably slow. A sudden and rapid exertion of the forces required to accomplish it would

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