50 REPORT OF THE SECRETARY. 



Bergland and Morrison ; (3) the office force in Washington, temporarily 

 in charge of Mr. George M. Lockwood. 



The two sections were rapidly organized, and, except in case of the 

 New Mexico party, were placed in areas readily approached, in order to 

 gain full advantage of the season, rendered necessarily short by the late- 

 ness of the appropriations. The results accomplished are of more than 

 usual value. The detailed topographical notes from that part of the 

 Sierra Nevada within which lies Lake Tahoe, surrounded by a 

 number of outlying miniature lakes, will admit of publication upon a 

 scale of 1 inch to 1 mile. Minute topographical details, by the plane- 

 table method, admitting of reproduction on a scale of 1 inch to 500 feet, 

 if required, were gathered in the vicinity of Virginia City, Nev., by a 

 party dispatched thither for the purpose of measuring a base-line. 



As the result of this season's barometric work, 749 cistern- oarometer 

 and 3,804 aneroid stations were occupied. The highest point reached 

 was Pike's Peak, 14,150 feet ; the lowest was Sulphur Springs, Nev., 

 3,575 feet. Fourteen mining-camps were visited. 



During the past year the following publications have been made : 1 

 progress-map; 2 crayon atlas-sheets 5 7 topographical atlas-sheets; 6 

 geological atlas-sheets ; map of Lake Bonneville, (restored outline of 

 an ancient fresh- water lake ;) preliminary report of 1869, revised edition ; 

 annual report of 1876; Volume III (Geology) of general report; Part 

 I (Invertebrates) of Volume IV, (Paleontology;) and Volume V, 

 (Zoology.) Progress has also been made upon Volumes I, II, VI, and 

 VII, and it is expected to have the MS. of three of them in the hands of 

 the printer at an early date. The manuscript for Catalogue of Declina- 

 tion of 2,018 stars has gone forward. 



The small amount of the appropriation did not admit of the employ- 

 ment of the usual number of geologists, zoologists, &c, but Mr. A. B. 

 Conkling, as geological assistant, and Mr. H. W. Henshaw, as zoological 

 collector, accompanied the California section. Observations in geology 

 were confined chiefly to the eastern and western summits of the Sierra 

 Nevada Bange. Abundant e\ idence of the former existence of glaciers 

 is found in the mountains on the southwestern side of Lake Tahoe. Gla- 

 cial scratches were observed on Tallac Peak. Vast surfaces of rock 

 have been polished and grooved by these moving masses of ice, and well- 

 marked terminal moraines are seen on the southern banks of the lake. 

 Some very picturesque lakes occur in front of Tallac Peak, and, accord- 

 ing to Prof. Jos. Le Conte, who has studied this region carefully, these 

 lacustrine areas have been scooped out by glacial ice. 



Near Lick's Point, Lake Tahoe, a compact phonolite is found. The 

 northern side of the lake is bounded by granitic ridges. In the Eastern 

 Summit there are several ore-deposits. The principal mines are the 

 Montreal, Emerald, Niagara, and Clear Creek Caiion. The Carson 

 Valley contains numerous hot springs, and several basaltic buttes occur 

 on the plain of Carson City. About one mile east of the town a mass 



