138 



Sierra Club Bulletin 



As to the character of the publication, may there be no mis- 

 apprehension : it is not to be technical or "dry," as scientific 

 writings are often accused of being by the pubUc; an effort 

 will be made to present the rather complicated story of the 

 Yosemite in simple, readable language, devoid as far as prac- 

 ticable of scientific phraseology and supplemented by numer- 

 ous illustrations. It is intended that the account shall be at- 

 tractive to the layman, that its pages shall speak to him, as 

 it were, instead of treating him in that coldly informational, 

 impersonal way that sometimes seems to forget that people 

 have souls as well as intellects. 



The party that was sent out by the United States Geologi- 

 cal Survey last year was composed of two geologists each of 

 which was to pursue a special line of study. Mr. F. C. 

 Calkins, a geologist of ripe experience (and a graduate of the 

 University of California) undertook the petrographic and 

 structural examinations, that is to say, the study of the char- 

 acters and relations of the different kinds of rock occurring 

 in the area ; while the writer was charged with the physiogra- 

 phic phases of the problem, that is, with the determination of 

 the mode of evolution of the features of the landscape. Both 

 men were to cover the same territory, their work being 

 mutually supplementary. 



Perhaps the reasons for this division of labor will not be im- 

 mediately apparent to the reader; it may therefore be well, 

 before entering upon an account of the manner in which the 

 work was executed, first to state what is the nature of the 

 Yosemite problem. 



Broadly speaking, it involves two questions: the more 

 specific one of the evolution of the Yosemite Valley, and the 

 more general one of the geologic history of the Sierra Nevada, 

 the mountain range in which the Yosemite lies hewn. The 

 latter history is a complex affair that takes one back through 

 several turbulent geologic periods, to times when great masses 

 of molten rock pressed up from beneath, invaded the surface 

 rocks and, possibly finding vent in orifices here and there, is- 

 sued forth in the form of lava flows ; and to a still earlier date 

 when the area now occupied by the Sierra Nevada was not 

 even land, but was covered by the sea, and received vast 



