THE PRE-SYMPOSIUM EXCURSION (July 17 -26,1998)
Cliff Ollier
The Paleopedology Commission of the International Quaternary Association held a conference at Lanzhou, with field excursions before and after. The pre-Conference excursion, with fifteen participants, was to Xinjiang (the most northwesterly of Chinese Provinces, and was very well organized and run by Professor Zhong Jun-Ping. We were told the weather would be warm and fine, and warned that “The area that we will pass is the most undeveloped area in Xinjiang. So the participants have to be mentally prepared.’’ We assembled at Kashgar - one group via Beijing and Urumqi, and the ‘Bronger’ group via Pakistan.
Sightseeing in Kashgar we visited the Abakh Hoja Tomb and Idkah Mosque, and of course the Bazaar, with its wild mixture of knives, meat, cloth, musical instruments, wool and exotic food.
We traveled from Kashgar to Hotan, about 500km over the Gobi Desert. This puzzled us at first because what we know as the Gobi Desert is thousands of kilometers away. It seems that ‘Gobi’ just means ‘stony’ desert, so there are lots of them. We visited the largest oasis on the footslopes of the Kunlun Shan (Mountains), and were impressed with the irrigation agriculture.
We had to abandon the bus the next day and use jeeps to visit Pulu village at the foot of the Kunlun Shan, which we saw only in the distance. We saw some ‘loess’. It was quite sandy, with original aeolian bedding, there were no vertical joints, no carbonate concretions, however, it shows many pseudomycelia as true signs of intense bicarbonate metabolism. This region may be where loess originates, not accumulates. In the same area we also saw patterned ground, some in good cross section. It resembled periglacial patterned ground in some respects, but it is gypsum, not ice, that crystallizes and expands. We visited the place where the local river is captured for irrigation further downstream, and a dam under construction for electricity production as well as for water control.
We stayed for lunch at Pulu village an oasis, where the men wear black fur hats despite the heat. They gave us beef stew cooked in traditional oven, and tea. It was all served in local house, where we sat cross-legged and ate with our fingers. On the return trip we examined the amazing Quaternary geology. The area consists of horizontal gravels over planated bedrock, with a couple of widespread basalt lava flows about 20 m thick. The basalt is 1.2 Ma old. There has been deep erosion since, but no folding.
We had very long day going from Yutan to Luntai, about 600 km across the Tarim Depression, and through the heart of the Taklimakan Desert. The road is modern, very good, and bordered by sand trapping devices. The sand is clearly still active, and constant work is necessary to keep the road open. The sand itself is an immature sediment, with plenty heavy minerals and mica. The road gives access to several oil fields, and oil is taken out by tanker. We stayed overnight at a guest house of one of the petrol companies and dined with the workers. Before, we crossed the Tarimu River, which is remarkably wide and very muddy but is still extracted for irrigation.
After the desert we crossed the southern Tien Shan to enter the Turfan Basin. Aiding Lake lies at the bottom of the depression, at an elevation of 161m below sea level, and is surrounded by a special irrigation system known as karez, which are man-size tunnels several kilometers long, with access holes about every 50 meters. Over 1000 karez have been dug, but now leakproof channels and pumped wells are replacing them. Only one third of the farming land is now irrigated by karez. We visited a karez museum to learn more about them, and also some very good oases growing grapes. It could be great wine country ! We visited Flame Mountain, Cretaceous Red Beds gullied to resemble flames when seen from a distance, and looked at a loess paleosol sequence.
We were supposed to leave Turfan at night and travel by train to Lanzhou, but the railway was washed out, so we had to overnight at Turfan, quite a nice town of perhaps 50 000 people and next day drive to Urumqi after crossing the central Tien Shan mountains. The first part was interesting, but the last hundred kilometers was in dreadful traffic. We eventually reached Urumqi.
We had a spare half day to fill in, so visited Urumqi Park and then the Museum which has some wonderful exhibits. The most interesting were the mummies, dried up but dressed in the clothes they wore when living. Most of them are westerners, and they date back to 3000 years ago.
Overall this was a great soil-geomorphology excursion. The fault block landscape of high mountains and deep depressions, combined with the general aridity and occasional oases provides a unique landscape. We also became aware of the many environmental problems brought by modernization, including the very rapid growth of cities and transport systems, and the changes in agriculture and water management. We feel privileged to have visited the area before it changes completely from its historic, “Silk Road’’ past.