34 PROCEEDINGS OF THE BOSTO^■ MEETING 



Wheeler should appeal to him to nominate a geologist for the new west- 

 ern work. He recommended Gilbert, who was at once appointed. 



Gilbert was 28 years old when his appointment as geologist with the 

 Wheeler Expedition transferred his field of activity to the West, and 

 although he was later to return and again to take up problems connected 

 with the history of the Great Lakes, upon which he had touched surely 

 and skillfully while with the Ohio Survey, the western fields and their 

 problems were now to command his attention and his energies exclu- 

 sively for the next decade. 



Gilberts connection with the Wheeler Survey lasted from the spring 

 of 1871 until December, 1874. Three of the summers were utilized in 

 extensive and rapid reconnaissances, under conditions that were none too 

 favorable for geologic work, and the fourth summer, that of 1874, was 

 devoted to the completion of the resulting reports. On the first of 

 these trips Gilbert left Eochester on April 21, 1871, arriving at San 

 Francisco May 2. 



The reconnaissance of that year carried him southward across central 

 Nevada, through Death A'alley and into Owens Valley, California, then 

 eastward to the Colorado Eiver at old Fort ^Mohave, above the present 

 site of ISTeedles. From this point began that remarkable boat trip up 

 the lower canyons of the Colorado to Diamond Creek. At Diamond 

 Creek the journey was resumed by pack train, and continued southeast- 

 ward through central Arizona to Camp Apache, then down the valley 

 of the Gila to its junction with the Colorado at Yuma. From Yuma 

 the party went by boat down the Colorado, and through the Gulf of 

 California and the Pacific to San Francisco, where it arrived on January 

 3, 1872. 



Gilbert's work during the following summer was confined to western 

 and central Utah, where he had his first introduction to Lake Bonneville 

 and to northern Arizona. During the summer of 1873 headquarters 

 were at Fort Wingate, and Gilbert's field was western Xew Mexico and 

 eastern Arizona from Fort Wingate south. 



The geologic results secured by the Wheeler Survey appear in volume 

 III of the reports of that organization and in the atlas. Gilbert's 

 written contributions are represented by two papers, the first containing 

 the results of his work in 1871-1872 in L^tah, Xevada, California, and 

 western Arizona, and the second his eastern Arizona and western ]N'ew 

 Mexico discussions, products of the work of 1873. 



The Basin Eange and plateau provinces were discriminated, the char- 



