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.
A hill or ridge of sand piled up by the wind is called a sand dune. Dunes may form wherever there is a lot of loose sand and enough wind to move it. Beaches and deserts are common places for dunes. A sand dune forms when the wind shapes sand grains into a mound or ridge.