The Western United States Part 18

[Ill.u.s.tration: FIG. 107.--SHIPPING COPPER MATTE]

The slag is dumped into a car and is carried outside, while the huge dish containing the copper and some slag is swung to the opposite side of the building, where its contents are cast into another furnace. A very strong blast of air is forced up through the molten ma.s.s in this furnace, and the remaining portion of slag is blown out at the top in a shower of glowing particles.

From the bottom of the furnace the liquid copper is drawn out and allowed to run into moulds where it finally cools. It is then known as copper matte. The copper still contains some impurities, and retains in addition whatever gold and silver may have been present in the ore. Most copper ores carry a small amount of these precious metals.

The heavy bars of copper matte are now ready for shipment to some manufacturing point, where they are refined still further and made into the various copper utensils, copper wire, etc. Copper is valuable for many purposes, as it does not rust easily, is highly malleable and ductile, and is a good conductor of electricity.

In the great copper-mines upon Lake Superior, copper is found in the native state mixed with the rock, and does not have to be smelted; but in most mines the ore must go through a process very like the one described before metallic copper can be obtained.

It does not matter how remote a region may be, how intense the heat or cold, or how desert-like the surrounding country, men will go to it if minerals of value are discovered; and there they will perhaps spend the whole of their lives, mining these substances which are of such importance to the industries of the world.

COAL AND PETROLEUM

People are beginning to ask where fuel will be obtained when the coal-beds are exhausted and the petroleum is all pumped out of the earth. The cold winters will not cease to come regularly, and we shall continue to need fires for many purposes. This is a question which need not trouble us. So long as the sun lasts in the sky and the oceans cover so much of the earth, and so long as there are mountains upon the land, there must be streams with rapids and waterfalls. The power of these streams, which has for ages gone to waste, is now being turned into electricity for purposes of light and heat. We may be sure that long before the mines cease to produce coal and the wells to supply petroleum, there will be something better ready to take their places.

But coal and petroleum are still such important commodities that everyone should know something about the way in which they were made. This earth of ours has had a very long history, much of which has been recorded in the rocks beneath our feet, and the record is more accurate than are many human histories which have been preserved in the printed books.

The story of the earth has been divided into different periods, each marked by the predominance of certain kinds of living things.

The Carboniferous period has been so named because at that time the climate and features of the earth in many places favored the growth of dense and heavy vegetation. This vegetation acc.u.mulated through the long years, so that it formed thick deposits which gradually changed to beds of coal. It would be wrong, however, to think that all the beds of coal were formed at about the same time.

Ever since there have been forests and marshes upon the earth there have been opportunities for the forming of coal-beds. Materials are acc.u.mulating even now which will in time be transformed to beds of coal.

We must be equally careful to gain correct ideas of the making of petroleum, for many wrong notions are current. While coal has come from the acc.u.mulation of plant remains, petroleum has been derived from sea organisms, chiefly animals. If coal and petroleum are found near each other, the occurrence is accidental and does not mean that the two substances are in any way related.

Our earth is very old, and its surface has gone through many transformations; mountains, plains, and portions of the sea floor have changed places with one another. Wherever there have been marshy lowlands, since plants first began to grow luxuriantly upon the earth, it has been possible for beds of coal to be formed.

We all know how rankly plants grow where there is plenty of heat and moisture. Many of us have been in swampy forests and have seen the ma.s.ses of rotting tree trunks, limbs, and leaves. Now, if we should form a picture in our minds of such a swamp slowly sinking until the water of some lake or ocean had flowed over it and killed the plants, and then washed sand and clay upon the buried forest until it was covered deeply in the earth, we should understand how the coal-beds began. Veins of coal that have been opened by the miners frequently show trunks and stumps of trees, as well as impressions of leaves and ferns. Underneath the coal there is usually a bed of clay, while above sand or sandstone is commonly found.

The oldest coal has been changed the most. It is hard and rather difficult to ignite, but when once on fire it gives more heat and burns longer than other coals. This coal, known as anthracite, is not found extensively in the United States outside of Pennsylvania.

Coal which is younger and has been less changed by the heat and pressure brought to bear upon it when it was buried deep in the earth, is known as bituminous. This is the kind of coal which is found in the Mississippi and Ohio valleys, in the Rocky Mountains, and upon the Pacific slope. A still younger coal, which is soft and has a brownish color, is called lignite, and is found mostly in the South and West.

Still another sort of fuel, known as peat, is found in swamps where considerable vegetation is now acc.u.mulating, or has acc.u.mulated in recent times. Peat is a ma.s.s of plant stems, roots, and moss, partly decayed and pressed together. In countries where wood is scarce peat is cut out, dried, and used for fuel.

The larger part of the coal in the eastern United States was formed during the Carboniferous period. That part of our country was then low and swampy; but the West, which is now an elevated area of mountains and plateaus, was at that time largely beneath the ocean.

Then, as the surface of the earth continued to change, the ocean retreated from the Rocky Mountain region, and extensive marshy lowlands with lakes of fresh or brackish water came into existence.

There were such marshes in the areas that are now covered by New Mexico, Colorado, Wyoming, Dakota, and Montana. Westward for some distance the land was higher, but in the states of Washington, Oregon, and California there were other marshy lowlands covered with heavy vegetation.

We know from what we have seen of the manner in which wood decays, that in the dry, open air it does not acc.u.mulate, but is in great part carried away by the wind. It is only in swamps and shallow bodies of water that the decaying wood can gather in beds. From these facts we have a right to draw conclusions as to the former nature of the surface where there are no coal-beds. There are extensive beds of limestone in the western United States which are of the same age as the coal-beds in the east. As such beds of limestone could have formed only in the ocean, their presence throws a good deal of light upon the geography of those distant times.

Upon the Pacific slope the marshes were not so extensive, nor did they last for so long a period, as those in the East. Nature seems to have confined her strongest efforts at coal-making to the country east of the Rocky Mountains. Perhaps she thought that the people of the West would not need coal if she gave them plenty of gold and silver.

In the Appalachian mountains Nature folded the strata and left them in such a position that the coal could be mined easily. In the Mississippi Valley the beds were left flat, almost in their original position, so that shafts had to be sunk to reach the coal.

Upon the Pacific slope Nature seems to have had a large amount of trouble in arranging things satisfactorily. She has made and remade the mountains so many times, and folded and broken the crust of the earth so severely where the swamps stood, that now large portions of the coal beds which once existed have crumbled and been washed away by the streams. The scanty supply of coal which now remains is in most places hard to find and difficult to mine.

[Ill.u.s.tration: FIG. 108.--SEAMS OF COAL ENCLOSED IN SANDSTONE, CALIFORNIA]

The best coal mined near the Pacific comes from Vancouver Island.

Large beds of a younger and poorer coal are found southeast of Puget Sound. There are other beds in the Coast ranges of western Oregon, and a few small ones in the Coast ranges of California.

The great interior region between the Rocky Mountains and the Coast ranges has very little coal. The people of California have to import large quant.i.ties of coal. Some is brought by the railroads from the Rocky Mountain region, but the most comes by ships from various parts of the world, from England, Australia, or British Columbia.

The ships bring the coal at low rates and take away grain and lumber.

Coal is almost the only important mineral which Nature has bestowed sparingly upon the Pacific slope. In California, however, she has made amends by storing up large quant.i.ties of petroleum. In Pennsylvania and Ohio there is petroleum as well as coal. Oil has also been discovered in the Rocky Mountain region and in Texas.

[Ill.u.s.tration: FIG. 109.--A SPRING OF WATER AND PETROLEUM

The black streak is petroleum]

Petroleum is found flowing from the rocks in the form of springs, either by itself or a.s.sociated with gases and strong-smelling mineral water. The oil is usually obtained by boring wells, but in southern California there is one mountain range which furnishes large quant.i.ties through tunnels which have been run into its side. Petroleum is commonly found in porous sandstones or shales, from one or two hundred to three thousand feet below the surface. It was not made in these rocks, but has soaked into them just as water soaks into a brick. The rocks which produced the oil or petroleum are dark, strong-smelling shales or limestone. Heat a piece of such rock, and you will drive out a little oil.

[Ill.u.s.tration: FIG. 110.--OIL WELLS IN THE CITY OF LOS ANGELES, CALIFORNIA

Pool of oil in foreground]

Examine a piece of the shale from one of the oil districts of California, and you will discover that it is a very peculiar rock, for it is made up almost wholly of minute organisms which once inhabited the ocean. Among the forms which you will find are the silicious skeletons of diatoms, the calcareous skeletons of foraminifera, scales of fish, and, rarely, the whole skeleton of a fish.

Where now there are mountains and valleys dotted with oil derricks, there was once the water of the open ocean. This water was filled, as the water of the ocean is to-day, with an infinite number of living things. As these creatures died, their bodies sank to the bottom, and while the soft parts dissolved, the hard parts or skeletons remained.

Through perhaps hundreds of thousands of years, the skeletons continued to acc.u.mulate until beds were formed hundreds or even thousands of feet in thickness. The materials of the beds, at first a soft ma.s.s like the ooze which the dredger brings up from the bottom of the present ocean, became packed together in a solid ma.s.s.

Then disturbances affected this old sea bottom. It was raised, and gravel, clay, and sand from some new sh.o.r.e were washed over the bed of animal remains, burying it deeply. Continued movements of the earth finally folded these rocks, which, as they were, squeezed and broken, became warm. The heat and pressure started chemical action in the decayed animal bodies, and particles of organic matter were driven off in the form of oil and gas. These substances were forced here and there through the fissures in the rocks. Part of the products found a way to the surface and formed springs, while other portions collected to form vast reservoirs in such porous rocks as sandstone. The sulphur and mineral springs which occur in oil regions tell us that this work of oil-making is still going on.

The oil as it comes from the ground is usually brownish or greenish in color, and much thicker than the refined product which we use in our lamps. Some of the crude petroleum is thick and tar-like in appearance, and when long exposed to the air turns to a solid black ma.s.s called "asphaltum." This, when softened by heat and mixed with sand, makes a valuable material for street pavement.

THE CLIMATE OF THE PACIFIC SLOPE

The western portion of the United States exhibits very interesting climatic features. In California, for example, there may be found every degree of temperature between tropic heat and arctic cold.

In the deserts of the southeastern portion of the state the air is extremely dry, while in the northwest it rains nearly every month in the year.

Upon the borders of Puget Sound the thermometer seldom falls below the freezing-point, while southern Newfoundland, in the same lat.i.tude, is marked by cold and snowy weather for at least six months of every year. Southern California has the same lat.i.tude as central Georgia, but its average temperature near the coast is but little higher than that of Puget Sound, while it is warmer in winter and cooler in summer than Georgia. The deserts of southern California and Arizona are so hot that for four months of the year work in the sun is almost impossible; yet the higher portions of the Sierra Nevada mountains, but a short distance away, have an arctic climate. The whole Pacific coast region has, with the exception of the mountains, a much milder climate than one would expect from a mere knowledge of its lat.i.tude. It will be instructive to search out the reasons for the remarkable contrasts in climate presented by different portions of the slope.

The imaginary lines pa.s.sing through points of equal temperature upon the earth are called "isotherms." These lines rarely accord in direction with the parallels of lat.i.tude, but curve far to the north or south. The irregular course of the isotherms is due to many causes. Among these are the distribution of the land and water, the direction of the prevailing wind, the position of the mountain ranges, and the elevation above sea-level.

[Ill.u.s.tration: WEATHER MAPS

Fair weather over central portion of Pacific slope. Storm coming in upon coast of Washington

Stormy weather over the western half of the United States]

In winter the isotherms curve far to the north over the North Pacific and North Atlantic oceans; but over the intervening land they curve as much to the south. In summer the isotherms are almost reversed in position, at least as far as the land is concerned, for they bend to the north in the heart of the continent. There are important reasons for the slight variation of the isothermal lines upon the western borders of North America and Europe, and their great change of position in the interior from winter to summer, but these reasons are not at all difficult to understand.

The temperature of large bodies of water changes but little throughout the year, for water warms and cools slowly. The surface of the land, on the contrary, heats rapidly, and then as quickly loses its heat with the changing season. The air over the ocean is cooler in summer and warmer in winter because of the influence of the water, but over the land, in districts far from a large body of water, the changes in temperature between day and night, summer and winter, are very great.

It was formerly thought that the warm j.a.pan current, which flows against the western sh.o.r.e of North America, was responsible for the exceptionally mild climate there, and that the Gulf Stream produced a similar climate upon the coast of western Europe. More careful study, however, has shown that not the warm ocean currents, but rather the winds blowing from the water, are the cause of the mild climate in those lands across which they blow. In temperate lat.i.tudes there is a slow movement of the air in an easterly direction, and in consequence the climate of the western coast of North America is not marked by such extremes in winter and summer as are the interior and the eastern sections. It is also surprising to find how nearly alike the average winter and summer temperature is at San Francisco. It is also surprising to note that the average temperature of Seattle differs so little from that of San Diego, although these two places are separated by sixteen degrees of lat.i.tude.