382 E. HUNTINGTON GLACIAL TERtOD IN NON-GLACtATED REGIONS 



not clothed with scraggly bushes, and their dunes are not mere little 

 heaps of sand 5 or 10 feet high. In the Takla-makan desert one can 

 travel scores of miles without encountering the slightest trace of vegeta- 

 tion, either dead or living. One travels there da}' after day over dunes 

 from 100 to 200 feet high, and occasionally over dunes which rose to 

 heights of 400 and even 500 or 600 feet, veritable mountains of sand. 

 To climb over a single one, about 400 feet high, took the camels of my 

 caravan nearly two hours. The Transcaspian desert is less rigorous than 

 the Takla-makan, but nevertheless it is a genuine desert. 



Along the edges of both deserts there are vast piedmont slopes of 

 gravel, sand, and silt washed down from the mountains. These are con- 

 stantly being built up by the deposits of streams and as constantly worked 

 over by the wind. The fmer materials are wafted away as dust, to be de- 

 posited upon the uplands in the form of loess, while the sand is heaped 

 into dunes. Near the edges of the deserts the sand is usually white, yel- 

 low, or pale gray, like that of ordinary beaches. Farther out, however, as 

 one gets away from the regions of recent deposition, it changes gradually 

 to a distinct pink color. I saw this transition many times, esjjecially in 

 the Takla-makan desert. It is so common a feature that among the natives 

 the term "kuzzil kum," or "red sand," is used to denote the real desert, 

 the region of great dunes and of no water or plants. More than once, 

 when I asked about traveling in a certain direction, I was told, "You 

 can't go there. It's red sand." The pink sand of tlie central parts of 

 the desert appears to be of precisely the same origin as the yellow sand of 

 the edges. The only difference is that it is of finer texture, and that its 

 oxidized iron has been dehydrated, thus changing its color. The cause of 

 the redness of hundreds of miles of sand in the Takla-makan and Trans- 

 caspian deserts, and also in Arabia, where similar conditions are reported, 

 is apparently the aridity of climate, which allows the sand to be long 

 exposed to tlie air without the presence, of plants. 



In view of all the facts, it seems highly probable that many of the 

 great non-fossiliferous red deposits of the earth which do not contain 

 marine fossils have originated under subaerial conditions, where the cli- 

 mate was very dry, at least during certain seasons. 



Summary of Conclusions as to the Pleistocene climatic Strophe 



In the study of the Pleistocene climatic strophe as a whole, it appears 

 that the investigation of glacial phenomena can best be supplemented by 



