Wednesday, 27 February 2008

The GREAT Sand Dunes

It surprising to see a desert surrounded by snowy peaks. But that's what makes Great Sand Dunes such as special place.


Click the image to see FULL SIZE DUNES !!

The dunes and surrounding area were designated a National Monument in 1932. On November 22, 2000, United States President Bill Clinton signed the Great Sand Dunes National Park and Preserve Act of 2000, aiming at ultimate national park status. With the help of the Nature Conservancy, the federal government purchased 97,000 acres (390 km²) of the Baca Ranch, which in effect tripled the size of the park. The purchase includes those sections of the ranch which previously bordered the park on the north and west sides and also included 14,165 feet (4,317 m) Kit Carson Mountain and 14,080 feet (4,292 m) subpeak Challenger Point, and the water drainages to the south. The land purchased was split into three sections. Part of the Sangre de Cristo Mountains would be transferred to the Rio Grande National Forest, another section to the west would be set aside as a wildlife area and would host a wild bison herd and the last section to the east would be transferred from the Rio Grande National Forest and would be open to some hunting.

The park contains the tallest sand dunes in North America, rising about 750 feet (230 m) from the floor of the San Luis Valley on the western base of the Sangre de Cristo Range, covering about 19,000 acres (77 km²).

The dunes were formed from sand deposits of the Rio Grande and its tributaries, flowing through the San Luis Valley. Over the ages, westerly winds picked up sand particles from the river flood plain. As the wind lost power before crossing the Sangre de Cristo Range, the sand was deposited on the east edge of the valley. This process continues, and the dunes are slowly growing. The wind changes the shape of the dunes daily.

There are several streams flowing on the perimeter of the dunes. The streams erode the edge of the dune field, and sand is carried downstream. The water disappears into the ground, depositing sand on the surface. Winds pick up the deposits of sand, and blow them up onto the dune field once again.

Digging a few inches into the dunes even at their peaks reveals wet sand. If the streams were to dry up, the dunes would disappear; in fact part of the motivation of turning the Monument into a National Park was the extra protection of the water, which Colorado's cities and agriculture covet.

It is very easy to experience the dune-building process. This is a very windy region, as hikers on the Sand Dunes will attest, as on many days they will be pelted by sand and even small rocks when hiking on the dunes. The wind carries sand and rocks from many miles away.

The dunes contain areas of black sand which are deposits of magnetite, a crystalline black oxide of iron.

Josiah doesn't seem too keen to climb the dunes.



Okay, can anyone tell me what is this??


We only make a stop here for about 3 hours, so apologise for such a lousy picture. Tomorrow, I'll post the best picture we had so far, the gem of Rocky Mountain, where heat meets cold.

No comments: