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.
The tallest stationary dunes are found in Mongolia, and they are over 1,600 feet tall. They also emit a constant hum that experts, to date, have not yet completely been able to explain. The tallest sand dunes in the United States are found in Great Sand Dune National Park in Colorado.