urban life of Paris.  The eastern lowland of England also can be differentiated economically and historically chiefly according to differences of underlying rocks, Carboniferous, Triassic, Jurassic, chalk, boulder clays, and alluvium, which also coincide often with slight variations of relief.[1045] In Russia the contrast between the glaciated surface of the north and the Black Mould belt of the south makes the only natural divisions of that vast country, unless we distinguish also the arid southeastern steppes on the basis of a purely climatic difference. [See map page 484.]

The broad coastal plain of our South Atlantic States contains only low reliefs; but it is diversified by several soil belts, which exert a definite control over the industries of the inhabitants, and thereby over the distribution of the negro population.  In Georgia, for instance, the rich alluvial soil of the swampy coast is devoted to the culture of rice and sea-island cotton, and contains over 60 per cent. of negroes in its population.  This belt, which is only 25 miles wide, is succeeded inland by a broader zone of sandy pine barrens, where the proportion of negroes drops to only 20 or 30 per cent. of the total.  Yet further inland is another fertile belt, devoted chiefly to the cultivation of upland cotton and harboring from 35 to over 60 per cent. of negroes in its population.[1046] Alabama shows a similar stratification of soils and population from north to south over its level surface.  Along the northern border of the state the cereal belt coincides with the deep calcareous soil of the Tennessee River Valley, where negroes constitute from 35 to 60 per cent. of the inhabitants.  Next comes the mineral belt, covering the low foot-hills of the Appalachian Mountains.  It contains the densest population of the state, less than 17 per cent. of which is negro.  South of this is the broad cotton belt of various rich soils, chiefly deep black loam of the river bottoms, which stretches east and west across the state and includes over 60 per cent. of negroes in its population.  This is succeeded by the low, coastal timber belt, marked by a decline in the quality of the soil and the proportion of negro inhabitants.[1047]

[Sidenote:  Value of slight elevations.]

In the dead level of extensive plains even slight elevations are seized upon for special uses, or acquire peculiar significance.  The Kurgans or burial mounds of the prehistoric inhabitants of Russia, often twenty to fifty feet high, serve to-day as watch-towers for herdsmen tending their flocks.[1048] Similarly the Bou-bous, inhabiting the flat grasslands of the French Congo between the Shari and Ubangui Rivers, use the low knolls dotted over their country, probably old ant-hills, as lookout points against raiders.[1049] The sand hills and ridges which border the southern edges of the North German lowland form districts sharply contrasted to the swampy, wooded depressions of the old deserted river valleys just to the north.  Early occupied by a German stock, they furnished the first German colonists to displace the primitive Slav population surviving in those unattractive, inaccessible regions, as seen in the Spreewald near Kottbus to-day.