0532 CHILE (Antofagasta / Atacama) - Penitentes from Puna de Atacama

Puna de Atacama (Atacama Plateau) is a cold Andean tableland in northwestern Argentina and adjacent regions of Chile, with a length of 320km (north to south), a width of 240km, and an average elevation of 4,500m. This region may be defined as the southernmost portion of the Andean Altiplano (Spanish for high plain) and is separated from the Atacama Desert by the Cordillera Domeyko. The peaks of the Cordillera Oriental alternate with dry, sandy, clay-filled basins, occupied by salt flats. Along its eastern margin, the plateau has been dissected by streams into deep, narrow river valleys, as well as broader valleys, important as colonial routes of penetration into the Argentine Andes. Peruvian and Chilean colonizers conducted expeditions through the Andean valleys in the latter half of the 16th century that led to the foundation of some of the oldest towns in Argentina. Before the War of the Pacific (1879-1883), the region belonged to Bolivia, but afterwards was ceded to Argentina (1898), and after the Puna de Atacama Lawsuit (1899) 85% from the disputed territory were awarded to Argentina and 15% to Chile.

One of the unusual natural phenomenon encountered on Puna de Atacama, on areas located above 4,000m, are Penitentes (also known as nieves penitents), which consist in ice or snow formations in the shape of thin blades, whose height can vary between few centimetres and five metres. The French glaciologist Louis Lliboutry is the one who explained the phenomenon in 1950's. He had concluded that Penitentes are a result of differential ablation. On high altitude, due to the dry air, the sun rays don't necessarily melt the ice, but instead they can change it directly into water vapor (sublimation). Some areas may sublimate more speedily than others, which may result in depressions on the surface of the snow. Sunlight gets concentrated on these curved surfaces, speeding up the process of sublimation in these areas resulting in the higher spikes of ice formations. It seems to me very interesting that the American Meredith Betterton developed a mathematical model of the process in 2001.

About the stamps
The first stamp, depicting the British Arch from Valparaiso, belong to the series Valparaíso, Patrimonio de la Humanidad, about which I wrote here. The second is a comemorative stamp, about which I wrote here.

The third stamp, with a denomination of 500CLP, depict (from what I understand) a sculpture from boxes by Colectivo Dimitri, named Whirlwind of Dreams in Time. The stamp was issued in 2011, with the occasion of First Competition of Urban Intervention with Boxes, which occured under the motto "Fits your ideas".

References
Puna de Atacama - Wikipedia
Atacama Plateau - Encyclopaedia Britannica
What are penitentes? - Innovateus
Penitentes - Wikipedia



sender: Hernán (direct swap)
sent from Santiago (Chile), on 13.12.2012