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CHAPTER VIII.

THE MINERAL TREASURES OF THE VALLEY.

The highest kind of power known to us is that which belongs to mind; that which organizes matter into living forms and so confers on it new offices and capabilities, is next lower, beneath which is the power residing in chemical attraction and repulsion; the mechanical force or weight of matterwhich measures the power of the attraction called gravitation -being the lowest. Intelligence has evidently superintended the operation of the lower forms of power, from first to last, and probably they are merely the modes in which the Supreme Intelligence displays its energy.

The earth has ever been a vast chemical laboratory. Mental and organic powers are scarcely more wonderful or mysterious than chemical force, and they seem dependent on it, in some form, for each of their innumerable manifestations. It is to this active agent and its extraordinary properties that the vast mineral accumulations of the Valley are due. It has acted with the greatest vigor where heat and moisture were abundant, and therefore its most stupendous deeds were accomplished in the early ages of the World, when the crust was thin, when the internal heat of the earth could make itself powerfully felt on the surface, and while the surface of the Valley was largely covered with water. The largest amount of mineral stores was usually accumulated at the point where these two elements met.

Most of the metals have been collected in large quantities by means of water heated by volcanic, or by chemical, forces and therefore along the lines where volcanic energies broke out. Yet, the largest accumulations of iron, the production

of coal and perhaps of lead, did not require, apparently, any great degree of volcanic heat for their immediate deposit. Here the more remote and gradual operations of heat led to the final result. Chemistry, as well as vital force, has had a graduated development to a certain extent. It had its special periods for the accomplishment of various tasks. Rocks of a certain composition could only be produced under certain circumstances, and different classes of metals must wait their turn to be gathered in large masses. There was a constant succession of services performed by chemistry for our Valley through the geological ages.

Iron is diffused very widely and abundantly through the rocks under many combinations. It is thought by some that the proportion is still larger in the center of the earth and even that it may constitute two thirds of the mass of the earth. The composition of the meteors-mostly iron-that have reached the earth from other spheres suggests this view, in which case the earth may be considered as ballasted with iron, and to have embodied in its true crust the larger quantity of its various other and lighter mineral substances.

Iron was specially abundant in the Azoic and primary rocks and the largest and purest beds date from that time. It is thought that beds of iron are always due to the chemical action of decomposed vegetable matter. The deposits of iron now being made are all accomplished in this way and it seems probable that it has always been done in the same manner, and that masses of this metal are both the evidence and the measure of the vegetation of the time and place of deposit. In this case evidence would be furnished of an extreme abundance of plant life on what have been usually called the Azoic rocks. The largest beds of iron known, and of a purity and excellence nowhere surpassed, lie along the south shore of Lake Superior. They are in the group of rocks formed immediately before the first of those known as Palæozoic, which contain the first well-preserved forms of ancient

THE IRON ORES OF THE VALLEY.

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animals. At that time this region was the southern shore line of the early continent.

Iron was more abundant, or more concentrated, in the early or Archæan rocks, and probably the vegetation of the time was chiefly seaweeds, lichens and possibly the coarse vegetation of marshes. The rains and streams leached out and washed down the iron of the surface rock of the land under various combinations, and the decaying vegetation of the bogsi and marshes of the shore caused it to be deposited in great abundance and purity at these points. It is said to equal in quality the best ores of the Old World, while the largest single deposits of that continent would be mere patches compared to the extent of this. The area of the Lake Superior mines is about 150 miles in length from east to west by a varying breadth of from six to seventy miles. Stretching along the shore of the lake the ore is peculiarly well situated for cheap and easy transport to the vicinity of the best and most abundant coals of Ohio and Pennsylvania.

Iron, apparently of the same age, is largely developed in Missouri-the very center of the Valley, and not distant from suitable coals for working it. Iron of this age is also found in Arkansas, in New York and New Jersey. Beds of it formed in various ages, and especially in the great Coal Age, are found in most parts of the country and very frequently in the neighborhood of coal areas. Although not so pure or so high in quality, it serves ordinary purposes well and is obtained and worked at a minimum of expense.

The use of iron is a measure of comparative civilization and enterprise. The iron of the Valley is far more important and useful to it than all the gold and silver mines of the whole world would be. The abundance of this valuable ore indicates the high rank this region is to take as a leader of future civilization.

The first group of rocks that contain animal remains hold veins of copper of great purity and unusual abundance in the

Lake Superior regions. This metal appears to have been collected in the cracks of the rocks under the influence of heat and certain chemical conditions. It is found in smaller quantity in Tennessee. The Valley now furnishes a much larger quantity than is required for use in this country.

Still higher series of the ancient rocks contain lead which is found in large quantities in a wide region covering corners of the States of Wisconsin, Illinois and Iowa and also in Missouri. Its deposit was not, apparently, due to volcanic action, but a special chemical condition of the time and regions caused it to collect or crystallize in the fissures of certain rocks. Great quantities of hard, beautiful and useful building stone, mainly from various limestone formations, follow in the ascending series and are very abundant for all common purposes through the upper Valley.

About midway between the earliest Palæozoic rocks and those belonging to the Carboniferous, or Coal-making Age, lie the series of formations in which was stored vast quantities of salt. All this is not confined, however, to one group of rocks. In different countries it has been made in different ages and the process is still going on in some places. It is only necessary that sea-water be confined in a bed so shallow that it may evaporate, when it deposits its salt. If this occur on the sea margin where, in high tides and storms, the salt water may be forced in now and then to evaporate as before, or if there is a very slow sinking of the surface for a long period to furnish occasional supplies to the salt-flat, very large quantities may be treasured up. When this is covered with formations of other rock, it is preserved.

If the salt was not formed under conditions to crystallize it into rock and the overlying formations are porous and admit water to it, salt springs are formed. The salt-bearing rocks of Michigan cover 17,000 square miles. These are found in Kentucky, and in various parts of the Valley, so that there is an abundant supply.

SUPPLIES OF PETROLEUM AND COAL.

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In the next higher series are the rocks which, in the northeastern part of the Valley, store up vast quantities of petroleum. This is believed to have been distilled by a suitable chemistry of these rocks, in the layers below or those above them, from vegetables and the soft parts of the bodies of animals. Some have thought it a pure mineral product-a combination of gases ascending from the heated regions of the lower rocks—and that the process is still going on. In this case the supply would be still more inexhaustible, but the general opinion is that this oil is a product of the Plant and Animal Kingdoms. Most of the rocks contain it in greater or less quantity. It is found in paying quantities only in porous rocks. This is sandstone in Pennsylvania and blue limestone in Kentucky. It added largely to the mineral wealth of the Valley.

But perhaps the most valuable mineral product of this region is its coal. It is necessary in vast quantities for working iron ore on a large scale, and it bears the most important relation to the wonderfully effective activities of modern industry. Great Britain has about 12,000 square miles of her territory underlaid with coal. It often lies very deep, and is there difficult and costly to raise; but it has made her the foremost nation of the world. The machinery used in manufacturing in Great Britain does the work of fifty million persons besides those employed to control it, and coal applied to transportation enables that country to develop trade and commerce to corresponding proportions. In the last seventy-five years, therefore, Great Britain has led the world in industry and commerce, and become the center of wealth among civilized nations. By means which find operative power in her coal she has acquired possessions and established colonies in every part of the world. Her aggressive spirit has been turned into useful channels, and she has been one of the most effective agents of civilization.

By her facility in manufacturing she overflows with this

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