January 8, 1897.] 



SCIENCE. 



49 



the Canyon of the Colorado in the former 

 year; he had A. E. Marvine as his assist- 

 ant in 1871, and E. E. Howell in 1872. In 

 1873-74 he extended his investigations 

 further south into New Mexico and Arizona, 

 -and in the following year left to join the 

 Powell Survey. 



Gilbert in his reports on the work of these 

 years (published 1875) did not pursue the 

 descriptive method in presenting the results 

 of his geological observations, but discussed 

 them at once as a whole under general 

 Leads. 



In this way he first characterized what 

 lie designated the ' Basin Range ' system of 

 mountain uplift, as brought about mainly 

 by faulting, in contrast to the structure of 

 the Appalachian Mountains, which is pro- 

 duced mainly by plication. The geologists 

 of the 40th Parallel regarded the uplift of the 

 narrow ranges of Nevada, from which the 

 term was derived, to be produced primarily 

 by folding, and that the faulting was a later 

 phase in Tertiary or post-Tertiary time, in 

 contradistinction to the more modern inter- 

 pretation of Basin Range structure as a 

 system of tilted beds without plication. 



His volume also contains able discussions 

 on land sculpture and erosion, on the Gla- 

 cial period, and the conditions attending 

 the drying up of the ancient lake which 

 once filled the Utah basin, and to which he 

 gave the name of Lake Bonneville, from 

 the explorer who first determined that the 

 basin has no exterior drainage. He also 

 had a chapter on recent volcanic manifesta- 

 tions and a section of the rocks shown in 

 the Canyon of the Colorado. 



In 1873 Prof. J. J. Stevenson was also 

 employed on the Survey and made a rapid 

 reconnaissance through the greater part of 

 ■Colorado. Hurried as this work necessarily 

 was, his report shows the grasp of mind of 

 the trained geologist, but his results were 

 soon superseded by the more detailed areal 

 work of the Hayden Survey. 



In 1874 E. D. Cope did some field work 

 as vertebrate paleontologist, and in 1875 

 Jules Marcou was attached to one of the 

 Californian parties and determined the 

 Tertiary age of the Tejon beds. In 1876 

 A. R. Conkling was attached to the Survey 

 as geological observer, and 1877 J. A. 

 Church made a second study of the Com- 

 stock lode, the results of which appeared 

 in a private publication. 



J. J. Stevenson was again attached to 

 the Survey in 1878 and 1879, with I. C. 

 Russell as assistant, during which time he 

 had an independent party under his own 

 charge, and he was making valuable con- 

 tributions to the geology of southeastern 

 Colorado and northern New Mexico, when 

 by legislative enactments the Survey came 

 to an end. 



From a geological point of view the sys- 

 tem pursued on the "Wheeler Survey was 

 less advantageous and, in proportion to the 

 expense, less productive of permanent ad- 

 ditions to geological knowledge of the 

 country involved than either of the other 

 organizations. The parties as a rule were 

 under the charge of a military officer, who 

 might have ideas of military discipline not 

 always consonant with the best interests of 

 geological work. 



Black Hills Surveys. Among military re- 

 connaissances the more important from the 

 geological point of view were those under- 

 taken as a result of the mining excitement 

 in the Black Hills, of the attacks upon 

 miners by the Sioux Indians, within whose 

 reservation they lay, and their consequent 

 appeals for government aid and for the 

 opening of the reservation for white settle- 

 ment. 



The reconnaissance across the southern 

 end of the hills, returning around their 

 northern flanks, which was under the com- 

 mand of Capt. Wm. Ludlow, in the sum- 

 mer of 1874, was accompanied by N. H. 

 Winchell and Geo. B. Grinnell as geolo- 



