Man's Role in Changing the Face of the Earth

activities aggradation agriculture American American Geophysical Union animals areas Basin belt canals cause cent century A.D. changes China civilization climate coal coast coastal crops cultivation culture desert drainage drainage basin early earth Ecology economic effect environment erosion Europe evaporation factors farming fertility fields fire fish flood forest Geographical Geological grassland ground ground-water growth human hydrologic cycle ibid Ice Age increase India industrial influence irrigation island lakes land loess London man's Marsh Mediterranean ment miles moisture natural resources Neolithic nomic noösphere North northern pasture peasant period plains plants Pleistocene plow pollution population precipitation processes production progradation rainfall regions result River runoff sediment slope Society soil square kilometer square miles steppe stream surface temperature tion town trees tropical ture U.S. Congress U.S. Geological Survey United urban Valley vegetation village western whales wood York