reconnaissance in turkestan 285 



Results in Physical Geography. 



Both our own observations and the excellent and extensive work 

 of the Russian geologists show that the progressive desiccation of 

 the region has greatly diminished both the area of cultivable land 

 and the volume of water, and greatly reduced the population. Is 

 this change a phase of cyclical phenomena — of cycles of long peri- 

 odicity ? In what relation have the geologically recent secular phe- 

 nomena in central Asia stood to man and civilization in that region 

 and to the outside world ? 



One of the chief objects of the reconnaissance of the past season 

 was to determine whether a systematic investigation would be likely 

 to throw light on these questions. Perhaps the most important 

 result is our finding that successive physical events have left such 

 abundant records, written in large strokes, all over the mountains 

 and the plains. 



The work of this year has not only made a most promising 

 beginning in this interpretation, but has shown that it is probably 

 possible to correlate the different events among themselves and with 

 the period of human occupation and possibly with similar physical 

 events in Europe. 



As an interior region, central Asia is arid and dependent for its 

 water almost wholly on its bordering mountains. It is also self 

 contained — i. e. , without drainage to the ocean. Changes of climate, 

 resulting in great fluctuations of water supply, would therefore 

 probably be recorded by old shorelines at different levels. They 

 might also be more or less legibly recorded in the evidences of 

 repeated glaciation and erosion in the high mountains. 



Professor Davis has found traces of an old shoreline about 600 

 feet above the west shore of the Caspian sea, and a very distinctly 

 marked one on the east side, at an elevation of 200 feet or more. 

 Further search for shorelines was left to form the object of a more 

 extended special study than could be made in our general recon- 

 naissance. 



In the Eastern mountains, near Issikul and Sonkul, Professor 

 Davis found clear evidence of two and probably three glacial epochs. 

 Mr. Ellsworth Huntington, working in Kashgaria, found proof 

 of three epochs, and later, of five in the successive moraines of a 

 large number of glaciers studied by him in the Alai mountains. 

 Between some at least of these there were long interglacial intervals. 



