As Location determines to a great extent the kind of society which may exist upon it, so also when location changes, society must make new adaptations. The change in the location may be the indirect result of man's own activity, thus exemplifying continuous variation again, and also Ross's statico-dynamic changes. The exhaustion of the forests of southern England is an example already noted. The soil of the South Atlantic states became exhausted from constant cropping with tobacco and cotton. This compelled the plantation owners to migrate westward and made a demand for more slave states. In general, the settlers in a new country exploit the virgin resources by producing some one or a few staple commodities; then after a time the exhaustion of these resources makes diversified industry necessary. Now neither of these two conditions comes from the deliberate choice of the settlers, either collectively or individually. Given the character of the people and the nature of the world market, the location itself virtually dictates how it shall be used by the first settlers and how by later occupiers.

One spring the school children dammed the brook which ran through one side of the school yard. The object was to run a small water wheel. The water wheel was put into operation, but also a neighboring garden was flooded. This flooding of the garden was a byproduct of the water wheel project and did not enter into the children's plan at all.

. . . The peculiarity of American institutions is the fact that they have been compelled to adapt themselves to the changes of an expanding people - to the changes involved in crossing a continent, in winning a wilderness, and in developing at each area of this progress out of the primitive economic and political conditions of the frontier into the complexity of city life. . . . Thus American development has exhibited not merely advance along a single line, but a return to primitive conditions on a continually advancing frontier line, and a new development for that area. American social development has been continually beginning over again on the frontier. This perennial rebirth, this fluidity of American life, this expansion westward with its new opportunities, its continuous touch with the simplicity of primitive society, furnish the forces dominating American character. ... - Bullock, Selected Readings in Economics, pp. 23, 24, Turner, "The Significance of the Frontier in American History."

Then, as appeared in the preceding chapter, location may change from physical causes. An example of this on a large scale was the drying up of Central Asia. The Tarim Basin once contained an inland sea where the desert of Gobi now is, and the surrounding lands were well watered. In time this sea dried up, except for a salt lake, Lob-Nor, remaining at the east end, and a vast region, once populous, became uninhabitable. This forced the people to migrate: China, India, eastern Asia and eastern Europe all felt the shock of invasion. The hordes precipitated upon Europe overthrew the Roman Empire, planted the Magyars in Hungary and the Turks in Asia Minor and the Balkan Peninsula, called forth the Crusades, and subjected Russia to the rule of the Tartars. Another example is the change in the location of the herring in the North Sea which contributed to the decline of the Hanseatic League and the rise of strong monarchies in the north of Europe.

There is much popular misconception, however, about changes in climate, for the reason that it exhibits cycles of change. These will be more fully considered in Chapter XV (Cycles Of Change).