Chlorofluorocarbons or CFCs are a chemical compound containing carbon, chlorine, and fluorine. Throughout the 20th century, CFCs were mass produced for their popularity in refrigeration and spray cans. In the 1970s, evidence began to show the harmful effects of CFCs on Earth.
Originally created as Great Sand Dunes National Monument on March 17, 1932, Great Sand Dunes National Park and Preserve was established by an act of the United States Congress on September 13, 2004.
Origin of Sand Dunes. The origin of sand dunes is very complex, but there are three essential prerequisites: An abundant supply of loose sand in a region generally devoid of vegetation (such as an ancient lake bed or river delta) A wind energy source sufficient to move the sand grains. A topography whereby the sand particles lose their momentum and settle out. Any number of objects, such as shrubs, rocks or fence posts can obstruct the wind force causing sand to pile up in drifts and ultimately, large dunes.