158 Prof. Backers Report on the U. S^ Coast Survey. 



I have now traced the influence of this thermal action from 

 two to three hundred miles on the Pacific coast in California, 

 but only in this place have I been permitted to witness its aston- 

 ishing intensity. The metamorphic action going on is at this 

 moment effecting important changes in the structure and con- 

 formation of the rocky strata. It is not stationary, but apparently 

 moving slowly eastward in the Pluton valley. 



I would respectfully invite the attention of geologists to this 

 cause of action, which hitherto has been too Tittle studied and 

 at present is not perfectly understood. The investigation will 

 probably aid in accounting for the existence of many springs inde- 

 pendent of ordinary Artesian flow, the formation of deep and va- 

 ried soils, of beds of sulphur, rock salt, chalk, clay, hydrous iron 

 ore, gypsum, ifcc, and perhaps extensive sections of breccia and 

 conglomerate like those which traverse our continent. 



California, March I'lth, 1851. 



,* 



Art. XV III. — Re-port of Prof. Alexander D. Bache, Superin- 



tendent of the United iStates Coast Su 

 gress of that work for the year endii 

 Doc., No. 12, 31st Cong., 2nd Session. 



Ex. 



c 



w 



4 



K ■ /J 



alloWj to the recent Report of Prof. A. D. Bache, Superintendent 

 of the United States Coast Survey, showing the progress and 

 state of that work, up to the latter part of 1850. *' 



Our readers may be presumed to be somewhat acquainted with 

 the nature of a work which has such an important bearing on the 

 great interests of our country, and the advancement of science. 

 We need, therefore, but briefly refer to the general plan and 

 scope of the Survey. 



The grand object — an accurate delineation of our coast and 

 its adjacent waters^ — is pursued by a system.; 1st, of primary tri- 

 angulation, founded on the nice admeasurement of a base line, 

 and embracing, wherever practicable, points of prominent inter- 

 est — accompanied by astronomical and magnetic observations, 

 for the determination of the latitude and longitude of such points, 

 and the variation of the compass; 2nd, of more minute triangu- 

 latiou, and accurate topography of the shores; and 3d, of hydro- 

 graphic observations, extending to all that may help the mariner 

 to a knowledge of the dangers or facilities of our coast naviga- 

 tion, in the present, and all that may point out to the government 

 judicious modes of indicating those dangers, or increasing those 

 facilities, in the future. 



The prosecution of this primary plan allows, and is used for, 

 the incidental promotion, not only of the discovery of phenom- 

 ena and laws which may afford new helps to the general science 



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