WORK OF THE PEESENT SURVEY. 19 



of the Califoruia Academy of Sciences." In these papers the possibility of an 

 outlet to the ocean for the waters of the Great Basin during the Quaternaiy 

 is suggested, and measurements are given of the altitude of some of the 

 passes in the northern part of Nevada which lead towards the drainage 

 of the Columbia. That the passes in this region could not have furnished 

 a point of discharge for Lake Lahontan will be shown in the following 

 chapter (page 34). 



The study of the surface geology of the Grreat Basin, undertaken by the 

 United States Geological Survey, was begun in the summer of 1880; a 

 section of the survey, entitled the "Division of the Great Basin," having 

 previously been organized under the leadei-ship of Mr. G. K. Gilbert, with 

 headquarters at Salt Lake City, Utah. The first field season was occupied 

 with the study of Lake Bonneville, the results of which have been pub- 

 lished by Mr. Gilbert in a somewhat popular essay in the second annual 

 report of the survey; the final report, in the form of an independent mono- 

 graph, is now in preparation. 



In April, 1881, the writer commenced a geological reconnaissance 

 through the northern part of the Great Basin, during which tlie northern 

 half of Nevada was crossed and recrossed, and excursions were made into 

 eastern California and southern Oregon. As the first year's exploration 

 was entirely of a preliminary character, without scientific assistants, all 

 detailed study and instrumental work was deferred until the following 

 season. The reconnaissance of 1881 occupied seven months, during which 

 about 3,500 miles were traversed in the saddle, the route being planned 

 with special reference to the study of Quaternary geology. During the 

 season the basin of Lake Lahontan was crossed in various directions and 

 much of its history was deciphered. A sketch of the geology of Lake 

 Lahontan, so far as determined from the first season's explorations, was pub- 

 lished in the Third Annual Repoi't of the United States Geological Survey. 



While carrying forward the reconnaissance of 1881, the Mono basin, 

 California, was visited and the study of its geological history begun; this 

 task was left unfinished, however, until the region could be topograph- 



'On the absence of a rim to the Great Basiu to the -west of Pueblo Butte, p. 223. Remarks on the 

 Topography of the Great Basin, pp. 270-27S. 



