IW Tin: KARTH AS MAN'S ABODE built lo check the formation of deeper gullies and to collect silt that would otherwise be washed away. Natural vegetation has been restored, and increased vigilance against disastrous forest fires has been established. As one passes through the great redwood empire of California and sees the stumps of huge forest trees which have been cut down, he questions the wisdom of such ruthless destruction of trees that required hundreds and thousands of years to grow. The even more irrevocable loss of soil does not disturb the average man because it usually takes place more slowly and less noticeably. However, trees will return in a few centuries, but it requires thousands and thousands of years to produce soil. The United States must not repeat the error that the Chinese made by deforesting and overtilling their fertile hillsides and thus providing conditions for a rapid run-off of heavy rains and melting snows. News items of very disastrous floods in China, covering thousands of square miles and driving hundreds of thousands of people from their homes, are a matter of almost yearly occurrence, while the very color of the Yellow Sea is a reminder of the soil which the Yangtze and Yellow rivers have carried to it. Terracing is being introduced to provide flat planes for clean-cultivated crops, the steep risers being protected by sod or other soil binders. Strip-crop cultivating is a variation of the terracing idea, in which strips of crops like sorghum or millet, which provide soil-holding mats of roots, are planted in concentric rings around a hill between the clean-cultivated crops. Contour furrowing is replacing straight furrowing on slopes. An effort is being made to retire poor farm lands from production to prevent erosion. The United States Government Is Now Engaged in Many Conservation Projects. Space will not permit the modern story of "Paradise Regained." All we can do is to point out a few of the results being obtained now that planning has come to be recognized as a function of a democracy and cooperation of an enthusiastic citizenry has put these plans to work. The waters of thirty-one states mingle in the Mississippi River, "The Father of Waters," each of whose frequent floods has destroyed property valued at hundreds of millions of dollars. Today the Mississippi River is hemmed in by 1825 miles of levees, twenty-one feet in height, that cost over one billion dollars. The Colorado River has been tamed by the construction of Boulder Dam. The great dams of
LIFE IS DEPENDENT UPON EARTH CONDITIONS 199 the Tennessee Valley Authority and those on the Columbia River represent efforts of men to cooperate with each other and with nature. The Bureau of Reclamation has built 165 dams to irrigate 4,000,000 acres of arid and semiarid land and at the same time prevent floods and generate power. The Central Valley Project in California is designed to prevent some 200,000 acres of rich lands from becoming a desert because of the lowering of the water table by extensive irrigation. Fig. 63. Sandhills Agricultural Project of South Carolina. Administration photograph, by Mundans.) (Resettlement The United States Government owns 750,000,000 acres of land, including valuable national forests, which it is wisely administering from the point of view of conservation. The Taylor Grazing Act of 1934 established the United States Grazing Service, which supervises the conservation of 142,000,000 acres of public grazing-lands. The Department of the Interior is carrying out soil conservation work on 285,000,000 acres of land, equivalent to one seventh of the area of the United States. The Civilian Conservation Corps, the Resettlement Administration, and many other government agencies have cooperated in a far-sighted program of conservation that demonstrates that democracy will and does work.