THE BASIN OF TURFAN 



375 



suppose that this is the case, there still remain at least four lacustrine 

 epochs preceding the five which can be correlated with the glacial epochs 

 of Europe and America. If we go to the other extreme and make the 

 number of lacustrine epochs as large as possible, we find that there is a 

 possibility that there were eleven preceding the five known in other 

 lands. Whichever interpretation we adopt, it appears that the Pliocene 

 and Pleistocene strophic period was highly complex. 



The Basin of Turfan, in Chinese Turkestan 

 general description of the basin 



At Turfan, 200 miles north of Lop-Nor, we find further evidence of 

 complexity. Turfan is a small basin of the same type as Lop and 

 Seyistan. Its aggraded floor extends about 100 miles east and west and 

 50 north and south. In spite of its extreme mid-continental position, 

 the lowest point of Turfan lies two or three hundred feet below sealevel. 

 Practically no rain ever falls on the basin floor. The high mountains to 

 the north and west receive enough rain to support a few perennial 

 streams too small to be called rivers. During the winter some of the 

 streams reach the playa of Bojanti, in the center of the basin. There 

 they form a thin sheet of water which dries up in summer. In spring, 

 when the snow melts, floods from the mountains sink into the gravel and 

 silt of the basin floor, and in the lower part convert scores or even hun- 

 dreds of square miles into an impassable bog of deep mud. Vegetation 

 springs up in the bog, but attains only a limited growth, as the country 

 soon becomes parched. A few hundred years ago, when the rainfall was 

 apparently larger, vegetation, chiefly reeds, grew far more abundantly. 

 The plain is full of an amazing number of reed stocks in places where 

 reeds can not now grow for lack of water. So abundant are the dead 

 reeds that the villagers who utilize tlie streams for irrigation make a 

 practice of digging out the dry stalks for firewood (see plate 35, figure 1) . 



The recent geological history of Turfan has been complicated by the 

 upheaval of the Fire mountains during the Pleistocene period. This 

 little range consists of a fault-block of red sandstone 5 or 10 miles wide 

 and extending 50 or 60 miles east and west- It divides the floor of the 

 Turfan basin into a northern third and a southern two-thirds. The 

 front slope of the range takes the form of a steep red escarpment nearly 

 2,000 feet high, rising abruptly on tlie north side of the fault-line, which 

 T\ms in an almost straight line east and west. The back slope toward 

 the north is very gentle. The sandstone of the upfaulted block of the 

 Fire mountains dips northward. The recency of at least part of the 



