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 famous sand dunes at Great Sand Dune National Park in southern Colorado formed in a valley from ancient lake bed. Large quantities of sand remained in the area after the lake breached. Predominant winds blew the sands towards the nearby Sangre de Cristo mountains.ypes of Sand Dunes. Crescent sand dunes, also called barchan or transverse, are the most common sand dune shapes in the world. They form along the same direction as the predominant winds and have a single slipface.