60 RESEARCH IN CHINA. 



age. His observations are described in the twelfth chapter, volume i, 

 of his work, on pages 552 to 559, but need not here be further considered. 



Obrutchov's journeys in northern Tibet were very extended. His 

 observations are unfortunately not fully available. The two great volumes, 

 Central Asia and Northern China, published in Russian, are in effect an 

 orderly transcription of his field-notes, from which it is difficult to obtain 

 an idea of geologic relations.* In his preface Obrutchov reserves all con- 

 clusions for a third volume, which is not yet available. He has, however, 

 found a most able interpreter in Suess, who supplemented the data found 

 in the volumes by correspondence with the author. I quote from him. 

 The region referred to lies in the heart of Asia, south of the Gobi desert and 

 north of the Tibetan plateau, between latitudes 35 and 40 north, and on 

 either side of longitude 100 east. The description includes an account of 

 rocks which are both older and younger than middle Paleozoic and in this 

 volume are systematically discussed elsewhere, but the quotation is best 

 given as a whole. 



Suess says:f 



The width of the Nan-shan, between the northern margin of the Tsai-dam and the 

 southern margin of the oasis of Kan-su, is equal to the width of the Alps between Biella 

 and Freiburg, and one may say that all the region commonly designated under the name of 

 Nan-shan corresponds approximately in extent to the Swiss Alps. The great height of 

 the ranges is accompanied, however, by a relatively even more striking altitude of the 

 valleys, a circumstance which diminishes the differences of level in the interior of the 

 mountainous region, but the observer is even thus below the limit of eternal snow. 



From Prevalsky to Roborovsky numerous but hardy observers have contributed to 

 knowledge of the topography of this mountainous region, but up to the present time only 

 two competent geologists have traversed it. The first was L6czy, whose researches out- 

 side of the northern border were strictly limited to the route from Lan-chrtu to Liang-ch6u, 

 to the valley of Si-ning and the southeastern part of the country. He was followed by 

 Obrutchov, who studied several sections across the northern ranges and in a long expedi- 

 tion traversed all the chains in the vicinity of their northwestern extremity. Thence, 

 following their direction, he reached the field of observation of L,6czy, south of the Ku-ku- 

 nor, and thereafter, crossing the eastern part of the ranges, regained the oasis of Kan-su. 



After commenting on the reconnaissance character of these investiga- 

 tions and the incompleteness of our knowledge, he says:J 



In the meridian of Sii-ch6u four high mountain chains rise between the oasis of 

 Kan-su and the longitudinal valley of Ku-ku-nor. They are uniformly directed west- 

 northwest. They are: the Richthofen range, the To-lai-shan, the range of Alexander the 

 Third, and a fourth chain which is little known and is separated from the preceding by a 



* In examining these volumes I have been greatly assisted by Mr. G. Zon, assistant forester, Bureau of 

 Forestry, U. S. Department of Agriculture. 



| La Face de la Terre, French edition, 1902; vol. in, part i, page 231. 

 %Ibid., page 232. 



