A people or race which, in its process of numerical growth, spreads over a large territory subjects itself to a widening range of geographic conditions, and therefore of differentiation. The broad expansion of the Teutonic race in Europe, America, Australia and South Africa has brought it into every variety of habitat. If the territory has a monotonous relief like Russia, nevertheless, its mere extent involves diversity of climate and location. The diversity of climate incident to large area involves in turn different animal and plant life, different crops, different economic activities. Even in lowlands the relief, geologic structure, and soil are prone to vary over wide districts. The monotonous surface of Holland shows such contrasts. So do the North German lowlands; here the sandy barren flats of the "geest" alternate with stretches of fertile silt deposited by the rivers or the sea,[212] and support different types of communities, which have been admirably described by Gustav Frenssen in his great novel of Joen Uhl. The flat surface of southern Illinois shows in small compass the teeming fertility of the famous "American bottom," the poor clay soil of "Egypt" with its backward population, and the rich prairie land just to the north with its prosperous and progressive farmer class. When the relief includes mountains, the character not only of the land but of the climate changes, and therewith the type of community. Hence neighboring districts may produce strongly contrasted types of society. Madison County of Kentucky, lying on the eastern margin of the Bluegrass region, contains the rich landed estates, negro laboring class and aristocratic society characteristic of the "planter" communities of the old South; and only twenty miles southeast of Richmond, the center of this wealth and refinement, it includes also the rough barren hill country of the Cumberland Plateau, where are found one-room cabins, moonshine stills, feuds, and a backward population sprung from the same pure English stock as the Bluegrass people. [Sidenote: Contrasted environments.] Here is differentiation due to the immediate influences of environment. The phenomenon reappears in every part of the world, in every race and every age. The contrast between the ancient Greeks of the mountains, coasts and alluvial valleys shows the power of environment to direct economic activities and to modify culture and social organization. So does the differences between the coast, steppe, and forest Indians of Guiana,[213] the Kirghis of the Pamir pastures and the Irtysh River valley, the agricultural Berbers of the Atlas Mountains and the Berber nomads of the Sahara, the Swiss of the high, lonely Engadine and those of the crowded Aar valley.