The other less used, but still commercially important, metals,—zinc, lead, and copper,—are found in considerable abundance in the Appalachian, the Laurentian, and the Cordilleran regions, especially in the last-named district. The only metal that is rarely found in North America, never yet in quantities of economic importance, is tin. Some specimens of bronze implements have been found in Mexico and Peru. They seem to afford the only evidence that the aboriginal peoples knew how to smelt any metals. Though the natives in the more northern districts used copper, they never discovered the art of smelting it.
Considering the useful metals as a whole, North America is proportionally richer than any other country that is well known to us.
The most considerable of the resources that the rocks of America offer, are found in the deposits of coal which they contain. These deposits are of vast extent, and are excellently fitted for the various uses of this fuel. While the other mineral resources of the country are most abundant in the region of the Cordilleras, the best of these deposits of coal are accumulated in and about the Appalachian district. At least nine tenths of the coal of America lies to the east of the Mississippi River. New England, New York, South Carolina, Florida, Mississippi, and Louisiana are the only States that are practically without coal; and even in New England, Rhode Island and the neighboring parts of Massachusetts have promising but essentially undeveloped fields. In the Cordilleran district coal deposits of small area occur; but the material is generally of poor quality, and is not likely to have a great utility.
As a whole, the resources in the way of subterranean fuel are far richer on this continent than in Europe. The area of coal-bearing rocks is at least eight times as great, and the deposits are much better disposed for working. No other continent save Asia is likely to develop anything like these coal resources; in China the coal area seems much larger than that of North America, but the richness of the field has not yet been fully proven: it is, however, undoubtedly great.
As the latent power of any modern society depends in an intimate way upon the buried stores of solar energy in coal-beds, the large area and good quality of the American coal-fields are very important advantages, and are full of promise for the economic future of its people.
Among the less important resources of the rocks in North America are the various classes of coal-oils which were first brought into commerce from its fields. Although these oils are not peculiar to North America, the small amount of disruption which its rocks have undergone have caused them to be retained in the subterranean store-houses; while in other countries, where the rocks have been more disturbed, these oils have been allowed to escape to the streams or the air. The areas where these oils occur on the continent are widely scattered. They are, however, principally confined to the Upper Ohio Valley; they are known to exist also in the Valley of the Cumberland River, in California, and in Western Canada north of Lake Erie. Besides these flowing oils there are immense areas of black shales, which yield large quantities of oil to distillation. These are not now of value, on account of the abundance of these flowing oils; but as in the immediate future these flowing wells are likely to cease their production, we may look to these shales for an almost indefinite supply of oil. In the Ohio Valley, extending eastward in Virginia into the valleys of the Atlantic streams, there is an area of over one hundred thousand square miles of this shale, which is on the average over one hundred and fifty feet thick, and yields about ten per cent of oil. In other words, it is equal to a lake of oil as large as New York and Pennsylvania, and fifteen feet deep,—a practically unlimited source of this material.
It is important to note that the sources of supply of phosphate and alkaline marls are very large. As these substances are subject to a constant waste in agriculture, and are the most important of all materials to the growth of the standard crops, the soil of America promises on the whole to be as enduring as is that of Europe, though, owing to the larger rainfall, it tends to waste away more rapidly.
The building stones of a country are of importance, inasmuch as they affect the constructions of a people; in such materials, suited for the purposes of simple strength and durability, the country is very well supplied, being quite as well off as Europe. On the other hand, the stones that lend themselves to the more decorative uses, the pure white or variegated marbles, are not nearly as rich as the countries about the Mediterranean, which is of all known regions the richest in decorative stones.
It is not possible within the limits of this chapter to support by sufficient details the foregoing statements concerning the physical conditions of America. The necessary brevity of the work has made it difficult to find place for all the points that should be presented; it may be fairly said, however, that the statements as made are to a very great extent matters of general information, which lie beyond the scope of debate, being well known to all students of American physiography.