EXPLOKATION OF THE MONO BASTN. 21 



The various routes followed by myself and my scientific assistants 

 during the exploration of Lake Lahontan are shown on Plate II, and will 

 serve to indicate the degree of completeness to which we were enabled to 

 carry our observations. A portion of the field season was devoted by Mr. 

 Johnson to the preparation of local maps, the positions of which are also 

 indicated on map forming Plate II. 



The winter of l'88'2-'83 was passed at the survey office in Salt Lake 

 City, in the preparation of notes and maps for publication, chemical studies 

 connected with our work, etc. In July, 1 883, I again took the field in 

 company with Mr. Johnson, and I'ecommenced work in the Mono basin. 

 After devoting all the time practicable to the study of the Quaternar}- 

 geology of that region T journeyed northward and passed through a large 

 portion of the Lahontan basin, en route to Eed Blufi", California, where I 

 disbMnded my party in October. In traversing the Lahontan basin I visited 

 sevei'al points of interest in the Walker River canon, about Pyramid and 

 Winnemucca lakes, and on the Black Rock and Smoke Creek deserts, thus 

 being able to review many previous observations. 



Mr. Johnson completed his topographical survey of the Mono liasin 

 late in December, and brought to a close, at least for the present, the field 

 study of the Qviaternary geology of the region from which the Division of 

 the Great Basin derived its name 



The explorations conducted by the writer have embi-aced three field 

 seasons, a part of each having been devoted to the study of Lake Lahontan. 

 The observations made during these several journeys, so far as they relate 

 to the great Quaternary lake of northwestern Nevada, are included in the 

 present report. 



Our work in the Mono basin during the same years that the explora- 

 tion of Lake Lahontan was being cnrried forward includes a study of the 

 existing lake and of the ancient lake of much greater extent thiit formerly 

 occupied the same valley ; ;dso, the relations of both the ancient and the 

 modern lake to the glacial and volcanic phenomena displayed on a grand 

 scale in the same basin. The results ftf these studies will be published 

 in the Sixth Annual Report of the United States Geological Survey. 



