The gateway of the old world The laden camel caravans with their cargoes of gemstones, silk and spic

The gateway of the old worldThe laden camel caravans with their cargoes of gemstones, silk and spices linking ancient Egypt, Greece and Rome with the luxuries of China along the silk road passed through; Genghis Khan and his hordes flowed through it to ravage China, the Middle East and Europe; Buddhists, Nestorian Christians, Hindu ascetics and Muslims all traded and cross pollinated ideas through it…This remote site at the border between the Xinjiang region of China and Kazakhstan is truly the most critical pass in Eurasian history.To the west, the endless steppe, ending in the Fulda gap in Germany (through which the Soviet armies were expected to invade back in my younger days). To the north, the inhospitable taiga of Siberia and Mongolia. In all the other directions, high mountains blocking the way: Pamir, Tien Shan, Hindu Kush, a litany of snow capped peaks. From Manchuria to Afghanistan it was the only true gateway in a 4,500 km wall of mountains created by the Himalayan Orogeny. Herodotus linked it with the legendary Hyperborea where the north boreal wind came from.Sine humankind’s migrations out of Africa, the Dzungarian Gate has been the main pass between the Middle Kingdom and Central Asia. And all these movements of history flowed from geology. The valley has such straight sides because it is a graben, a block of rock bounded by two normal faults that has sunk downwards between the surrounding mountainous blocks.The block is 10km wide and 46 long, plenty of room for a Mongol horde. Two lakes sit at either end, Alakol to the west and Ebinur to the east. The surrounding mountains are 3,000m high to the north and 4,550 to the south, while the pass is at a mere 450m, giving an idea of how far that block of rock has sunk into the crust. The responsible fault is the Dzungar strike slip fault, where blocks grind past each other, locally pulling the crust apart to sink the graben.LozImage credit: Karen Nyberghttp://spaceflight.nasa.gov/gallery/images/shuttle/sts-85/html/sts085-503-061.htmlhttp://www.britannica.com/EBchecked/topic/175433/Dzungarian-Gate -- source link

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