Great Sand Dunes National Park and Preserve
The Great Sand Dunes ( German Great Sand Dunes ) are as a National Park ( National Park and Preserve ) designated habitat area in the southern part of the U.S. state of Colorado. About 230 km south of Denver are the Great Sand Dunes in the northeastern part of the San Luis Valley, an approximately up to 60 km wide basin between the Sangre de Cristo Range and the San Juan Mountains. They cover an area of 80 km ² and are equipped with a height of about 230 meters, the highest sand dunes in North America.
History
The sand dunes are about 12,000 years old and created by sand deposits of the Rio Grande and its tributaries. Over thousands of westerly winds have blown the sand grains of the river banks through the valley and deposited on the east side, at the foot of the Sangre de Cristo Range. Through the mountains, the wind speed is slower and the sand and small stones were piled up into dunes. This process continues and changes daily in the form of dunes.
Through many small streams in the San Luis Valley, the sand absorbs water, causing it to be heavier and can no longer be carried away by the winds. Even at the highest point of the dunes of sand a few inches below the surface is wet. As the dunes over time would disappear with the drying up of streams, ensuring the water supply was one reason for the establishment of higher protection status as a National Park in 2000.
An extraordinary phenomenon can be observed in Medano Creek, a creek east of the dunes near the visitor center. Because fresh sand will flow evenly into the water, the river is no stable and enduring riverbed. This results in small underwater sand dunes that form dams and collapse again. This results in intervals surf waves, which can be up to 30 inches high at times in high water.
National park
The area around the dunes was declared on March 17, 1932 National Monument. On 22 November 2000, the then U.S. President Bill Clinton signed a law establishing the National Park ( Great Sand Dunes National Park and Preserve Act of 2000), after the land area of the protected area was enlarged and the Congress had approved the bill. The expansion areas subject to less protection status of a National Preserve where the practice is permitted. Officially, the National Park on 13 September 2004 was opened.