BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 5, pp. 489-514, PL. 19 APRlL 21, 1894 



GEOLOGICAL SKETCH OF LOWER CALIFORNIA 



BY S. F. EMMONS AND G. P. MERRILL 



{Presented before the Society December 29, 1893) 

 CONTENTS 



Page 



Introductory 489 



Physical Structure 490 



Geological Structure 495 



Observations by previous Investigators 495 



The Region under Consideration 499 



General Remarks on its geological Structure 499 



Coast or Mesa Belt 500 



Western Range 503 



I nterior Valley 505 



« Eastern Range 507 



General Conclusions 512 



Introductory 



So little is accurately known with regard either to the topography or 

 the geology of the peninsula of Lower California that it seems desirable 

 to put on record whatever new facts may be learned concerning either, 

 even though derived, as in the present instance, from observations made 

 during hasty trips into its interior for other than strictly geological pur- 

 poses. 



Of the topography of the peninsula the only reliable data published 

 are found on the charts of the United %States H^^drographic Office (the 

 Narragansett, 1873-75, for both coasts, and the Ranger, 1887, for the west 

 coast), which give the immediate coastline and topographical sketches 

 of the adjoining country for a few miles inland .'=^ The few maps of the 

 interior, whether published or in manuscript, that have been consulted 

 show so much discrepancy with one another and with actual natural 

 conditions, where comparison has been possible, that but little reliance 



* The map given on plate 19 is copied from the best reduction made by the United States Coast 

 and Geodetic Survey, and though its scale is too small to show details, it serves to express the 

 general outlines.of the coast and show the location of the various points mentioned. 



LXVIII-BuM.. Geol. Soc. Am., Vol. 5, 1893. (489) 



