CONCLUSION. I I 7 
CONCLUSION. 
Many problems that are touched upon in this and the following reports deser\-e 
much more study than we have been able to give them thus far. Some of them 
bear directly upon the objects of our expedition ; some are of general interest. Of 
the first class, the oscillations of the Caspian stand preeminent, and the desert 
depression, known as the Ungus, seems to be the most important district for next 
examination in this connection. In view of what is known of climatic variations 
during Quaternary time in other parts of the world, it is hardly possible that the 
Aralo-Caspiau history is of only one expansion; and whatever complications it 
experienced would probably have left their record on the bluffs and slopes that 
border this desert depression. At the same time, the confirmation of our conclusions 
regarding the complexity of the Glacial period b}- further study of moraines and 
terraces, especially in the Alai ranges and the Pamir, is much to be desired. Then 
would come the connection of these two classes of unlike records — lacustrine and 
glacial — by aiu- means that can be devised, along the mountains on the south or 
across the desert plains, thus gaining a correlation of the events of Quaternary 
time in the three physiographic provinces of the western Asiatic region and 
bringing the archeological remains of the plains into their place on the geological 
time-scale. Of subordinate value, but by no means unimportant, are the problems 
connected with the deposits of loess. Those south of Jizak deserve first attention. 
Issik Kul is a problem by itself Geology, physiographj-, and archeology- are 
there combined in the most inviting manner. A long season in that field alone 
would be highly productive. 
.Vn outstanding problem of importance in its bearing on theoretical geolog)' is 
found in the structure of the Tian Shan ranges. For this purpose the region could 
be entered to ad\-antage from the north, and a deliberate stud}- made of the pene- 
plains and fault-block mountain ranges o\-er which our party had to pass so rapidly. 
Few finer fields are open to the investigator. 
