THE quest of iron and copper and flint for use as weapons, and of gold and silver and precious stones for adornment, runs far back into history and is associated with many stirring events of exploration and war. But they were used on a relatively small scale and served only as a minor factor in the environmental conditions controlling human activities. With the advent of the industrial revolution of England, a century ago, began the real exploitation of earth materials in a way to influence essentially our material civilization. In this short time, at an ever accelerating rate, minerals have become the fundamental basis of industrialism, to be ranked with soil, climate, and other major influences on our activities. In these hundred years the output of pig iron has increased 100-fold, of mineral fuels 75-fold, and of copper 63-fold. In the last fifty years the per capita consumption of minerals in the United States has multiplied fifteen times. By harnessing up the power from coal, gas, and water we have multiplied our capacity for work. The acceleration of the rate of mineral exploitation may be realized from the fact that the world has exploited more of its resources in the last twenty years than in all preceding history.
In appraising the effect of this new element in human environment we have no historical precedent to guide us, for the change is too recent, too all-pervasive, for us to understand all its significance. Yet a few clear tendencies are beginning to be discernible.
The rising use of mineral resources has naturally led to an intensive search of the earth for adequate supplies, which is just beginning to give us some realization of their ultimate geographic distribution. Changes will still be made by discovery, usually in expected fields, but the main outlines are now pretty well fixed. The curve of geographic discovery is falling. The great discoveries of the future will in the main relate to better methods of recovery and use. As