284 CARNEGIE INSTITUTION OF WASHINGTON. 



surveying the mountains the relations of these two series to earlier 

 and later ones have been more exactly determined, and the con- 

 stituent members of each series have been noted. Two points of in- 

 terest may be stated : a conglomerate in the Wutai schist contains 

 pebbles of quartzite derived from an older sedimentary formation 

 which has not been surely identified in place ; and with reference 

 to the lyower Sinian, its relation to the Upper Sinian (Cambrian) 

 was observed along an extensive contact and found to be that of 

 marked unconformity. The L,ower Sinian therefore falls out of the 

 Cambrian and takes a position in the geologic column parallel with 

 that of the Belt terrane of the northwestern United States. Ift the 

 Belt terrane, after prolonged search, Mr. Walcott discovered certain 

 fossils, the oldest definite forms known. The Lower Sinian was 

 examined by us for fossils without success, but the strata are of 

 limestone and shale favorable to the preservation of organic remains, 

 and, considering the rare occurrence of the earliest fossils, the nega- 

 tive result of this preliminary survey should not be considered final. 

 The lyower Sinian may repay exhaustive study by results of which 

 only exceptional localities offer any prospect anywhere in the world. 



CONTRIBUTIONS TO THE HISTORY OF MOUNTAINS. 



The Old Viciv and the New. — When Baron von Richthofen made his 

 observations in China the view prevailed that mountains were fixed 

 features of the earth's surface, which dated in any particular case 

 from a geologic age, however remote, represented by the youngest 

 rocks in the mountain structure. This view is expressed in all the 

 accounts of Asia by European scientists. In America, during the 

 last fifteen years, through the study of topographic forms, it has 

 been shown that the mountains of this continent are relatively 

 recent features as compared with the rocks composing them, and 

 owe their elevation to forces acting during the latest geologic periods 

 down to the present. It was a point of prime interest in the com- 

 parative geology of continents whether the American methods of 

 study applied to Asia would show that mountain growth had re- 

 cently been active there also. The observations of this expedition 

 demonstrate clearly that the histories of mountains in North America 

 and China run closely parallel in time, in manner of development, 

 and in resulting features of relief. The studies of Professor Davis 

 in western Asia point in the same direction, and the (as yet unpub- 

 lished) investigations of Professors Penck and De Martonne in the 

 Alps and Karpathians extend the generalization to central Europe. 



