II. Land Forms.—The effect of the form of the lands can be readily seen. The prairies of southern Illinois and the most rugged parts of West Virginia differ relatively little in climate, and only moderately in soil awl altitude. But they differ gm tly in density of population because rugged mountains provide alntrt no place for people to live. Because of relief such people as the Dutch move about freely and come in contact with their neighbors, while others, like the Tibetans, are hemmed in by steep slopes, impassable valleys, and snowy passes.
III. Water Bodies.—Oceans, lakes, and rivers often separate country from country, and thus lead to great differences in race, language, and customs. On one side of the English Channel the people speak English and on the other French partly because the intervening body of water has prevented free intermingling. Bodies of water also serve as means of co_ and thus link people together. The hunter in Canada would find it difficult far through the forest if he could not use his 1?ark...=ine cy many lakes and rivers. On a larger scale the harbors of New Liverpool, and Amsterdam, with their throngs of great ships, prove how closely the oceans link country to country.
IV., Soil and Minerals.—A large part of the world's wealth comes from the soil. Where the soil is fine-grained and deep, as in the plains of northern France and Ohio, the farmers are prosperous. A poor sandy soil, even with a good climate, may make a region poverty-stricken. For instance, in Mississippi and Alabama the chief physical difference between the sandy pine belt and the rich fine soiled " black belt," where cotton grows, is the soil; but this differ ence makes one region the home of poor farmers who can scarcely get a living, unless large quantities of fertilizers are mixed with the soil, while the other is one of the most prosperous parts of the South.
Mineral wealth, as well as soil, is of vast importance. Without meill:bearing ores like those of the Upper Peninsula of Michigan, there would be no such thing as the machinery which runs the mills of Massachusetts. 'Other minerals such as the coal of Pennsylvania, and the petroleum of Texas, are the chief source of power for manu facturing and commerce. After the Great War the demand for petroleum was so insistent that every one of the great powers, in cluding even Russia in the midst of its revolution, sent a commission to Mexico to try and get a share in that country's oil. At the same time the stricken people of Europe, who were almost starving, were crying to 'the United States for minerals, especially coal, almost as urgently as for food.
V. Climate.—The last of the five great features of physical envi ronment is the most important. Climate enters into each of the other r four, as shown by the arrows in Fig. 1. It depends on location; it is greatly influenced by land forms and water bodies, and influences them in return; and it has a great effect on the character of many soils. For example, the difference between the desert climate of the coast of Peru and the wet climate of the forested headwaters of the Amazon in Brazil is wholly due to the form or relief of the Andes.
On the other hand, the sand dunes of western China are the result of a desert climate, while the "Black Earth" region of Russia owes its rich soil to a moist climate.
Climate also determines the character of the plants and animals in different regions. It causes oranges and bananas to come from Costa Rica, and wheat from Minnesota. Still more important is the fact that man's energy depends largely upon climate. The Costa Rican planter cannot possibly work as hard as the Min nesota farmer. In the far North not only does the climate cause the Eskimos to be poorly nourished, but the steady cold benumbs their minds and bodies, and prevents progress. In the Congo forests, on the other hand, it hampers progress by favoring malaria and other deadly diseases. Only in countries like England, where the weather is variable, and not too extreme, can man be at his best.
A. Plants.—It is almost impossible to think of the five great features of physical environment without also thinking of plants. The location of Greenland reminds us of the absence of vegetation and the consequent impossibility of man's getting a living. When land forms such as plains, are mentioned, broad acres of rich crops come to mind, while the word "mountains" brings a picture of rough slopes covered with forests.
Even water bodies influence man through the minute plants which make it possible for fish to inhabit their cool depths, and thus lead men out over the stormy seas as fishermen. When it comes to soil there is almost no reason for thinking of it except as it enables corn, wheat, or grass, for example, to grow richly as in Iowa, while in other regions, such as the sandy parts of Cape Cod, it makes the crops almost too poor to be worth harvesting. Finally, to many people, the chief indication of climatic differences is vegetation. The date palm stands for dry hot deserts, the cocoanut palm for moist tropical coasts, the cotton plant for somewhat more temperate regions, and tundra moss for an arctic climate.