US Geological Survey
Usgs: Effects of Human Activities
This site reviews the effects of agricultural development, urban and industrial development, drainage of the land surface, modifications to river valleys, and modifications to the atmosphere have on ground water and surface water.
Khan Academy
Khan Academy: Native American Culture of the Southwest
This article discusses the Ancestral Pueblo people who lived in the southwestern region of the modern United States; they constructed elaborate buildings and began the American farming tradition.