132 THE DESICCATION OF LATER GEOLOGICAL TIMES. 



According to various trustworthy authorities, and especially Richthofen. — 

 whose great woi'k, entitled " China," is a treasure-house of information in 

 regard to that country and Central Asia in general, — a vast area, lying 

 between the Kuen-Luen on the south and the Thian-Schau and Altai ranges 

 on the north, has been covered by water until within comparatively recent 

 times. To quote Richthofen's words : " It is a well-established fact, that the 

 ocean, at the end of the Cretaceous period, filled the Han-Hai ; that stratified 

 deposits were formed in it, for which the material (sand and gravel) was furn- 

 ished by the rivers flowing down [fiom the adjacent mountains] ; that this 

 inland sea had a communication with the great ocean, up to an indetermi- 

 nate later period, through the Djungarian basin or depression [die Dsun- 

 garische Mulde]. The Han-Hai is an elongated depression, extending in a 

 west-southwest and east-northeast direction, the western portion of which, 

 where least elevated, near Lake Lop (Lob-Nor) is probably not more than GOO 

 meters above the sea-level, while the deepest depression of the eastern part 

 is 607 meters in elevation. This now diied-up inland sea, the Han-Hai of 

 the Chinese, had — placing its western limit in Ion. 75° 30', and its eastern 

 in Ion. 114° 30' — a length of over 1,800 geographical miles, which nearly 

 equals that of the Mediterranean. 



" Communication having been cut off between the Han-Hai and the ocean, 

 there was left a great closed basin or inland sea [grosses Binnenmeer], which 

 by gradual evaporation became divided into several smaller basins, and these 

 again gradually diminished in size, some having become quite dry, while 

 others have not yet entirely disappeared, but form salt lakes. The retreat 

 [Riickzug] of this sea may possibly be connected with the period of volcanic 

 activity which has left its traces in the Thian-Schan and in Eastern Mongolia. 

 But nothing is definitely known in regard to the precise time of the forma- 

 tion of this inland sea or its development." * 



Richthofen does not, as will be observed, profess to go into any details as 

 to the character and origin of the orographic or climatic phenomena which 

 accompanied, and presumably brought about, this great change in the physi- 

 cal geogi'aphy of so extensive an area. He cannot, however, avoid noticing 

 that such a succession of events as he describes indicates the prevalence 

 of a dry climate during the later geological periods, for he says ; " It may 

 be stated as a certainly ascertained fact, that in Central Asia a dry climate 



• China, Vol I. p. 108. 



