1239, 1271 UNITED STATES (New Mexico) - White Sands National Monument (UNESCO WHS - Tentative List)

Posted on 23.09.2014, and 06.10.2014
Located in  the mountain-ringed Tularosa Basin, at about 25 km southwest of Alamogordo, at an elevation of 1,291m, White Sands National Monument comprises the southern part of a 710-km² field of white sand dunes composed of gypsum crystals (the largest gypsum dune field in the world). Gypsum is rarely found in the form of sand because it is water-soluble, and normally rain would dissolve the gypsum and carry it to the sea. The Tularosa Basin is enclosed, so that rain that dissolves gypsum from the surrounding San Andres and Sacramento Mountains is trapped within the basin. Thus water either sinks into the ground or forms shallow pools which subsequently dry out and leave gypsum in a crystalline form, called selenite, on the surface.

During the last ice age, a lake known as Lake Otero covered much of the basin. When it dried out, it left a large flat area of selenite crystals which is now the Alkali Flat. Another lake, Lake Lucero, at the southwest corner of the park, is a dry lake bed, at one of the lowest points of the basin, which occasionally fills with water. The ground is covered with selenite crystals which reach lengths of up to 1m. Weathering and erosion eventually breaks the crystals into sand-size grains that are carried away by the prevailing winds, forming white dunes. The dunes constantly change shape and slowly move downwind. Since gypsum is water-soluble, the sand that composes the dunes may dissolve and cement together after rain, forming a layer of sand that is more solid and could affect wind resistance of dunes. This resistance does not prevent dunes from quickly covering the plants in their path.

Many species of plants and animals have developed very specialized means of surviving in this area of cold winters, hot summers, with very little surface water and highly mineralized ground water. One of the genus of plants which survives on dunes is Yucca (in the postcard), the most common species being Soaptree yucca (yucca elata), which grows from 1.2-4.5m tall, with a sparsely branched trunk. The trunk is brown, cylindrical in shape and has a small diameter and often has holes drilled by escaping yucca moth larvae. The leaves are arranged in a dense spiral whorl at the apex of the stems, each leaf 25-95cm long and very slender, 0.2-1.3cm broad. The white, bell-shaped flowers grow in a dense cluster on a slender stem at the apex of the stem, each flower 32-57mm long, creamy white, often tinged pinkish or greenish.

About the stamps
On the first postcard
About the first stamp, featuring a portrait of George Washington, I wrote here. The following stamp, depicting Navajo Necklace (2c / 2006), is part of the definitives series American Design (2002-2007), about which I wrote here. The last stamp, depicting Shirley Chisholm (1924-2005), is part of the series Black Heritage Series, about which I wrote here.

On the second postcard
About the first stamp, featuring a portrait of George Washington, I wrote here. The following stamp, depicting Silver Coffeepot (3c / 2005), is part of the definitives series American Design (2002-2007), about which I wrote here. The last two stamps, dedicated to Lydia Mendoza (1916-2007),
respectively Johnny Cash (1932-2003), are part of the series Music Icons Forever, about which I wrote here.  

References
White Sands National Monument - Wikipedia
White Sands National Monument - UNESCO official website
White Sands National Monument - National Park Service official website

Sender 1, 2: Denise 
1, 2: Sent from Greenvale (New York / United States), on 27.03.2014 
Photo 2: David Muench / 1996