26 PROCEEDINGS OF THE CALIFORNIA 



the range between Mariposa and Shasta Counties. Our observations have also 

 been extended to the Washoe Region, and we have received considerable collec- 

 tions of fossils from the Humboldt Mining District, (known by this name on 

 the Pacific Coast, but designated on Warren's Map as the " West Humboldt 

 River Range," and in longitude 1 80°) by which we have been able to fix the 

 age of the formations in that region. 



Mr. Gabb has been chiefly occupied, the past year, in figuring and describing 

 the cretaceous fossils of the Coast Ranges and the foot-hills of the Sierra, of 

 which he has nearly two hundred new species ready for publication. He has 

 also described the triassic fossils, collected by the Survey at Washoe, and by 

 Gorham Blake, Esq., in the Humboldt Range. The fossils older than the 

 Trias have been referred to Mr. Meek for investigation. A portion of the fos- 

 sil plants have been placed in the hands of Dr. J. S. Newberry for description. 



It is to the department of General Geology that, up to the present time, by 

 far the greater portion of our attention has been given, since the first thing 

 required in a geological survey is a knowledge of the general geological struc- 

 ture of the State, the age of the various formations which occur in it, and their 

 range and extent, or the position which they occupy on the surface, and their 

 relations to each other. Each group of strata, thus determined by its litholog- 

 ical peculiarities, and by the fossils which it contains, is then to be laid down 

 upon the map, in the position in which its outcrop occupies on the surface. 

 The general character of the minerals and ores which occur in each formation 

 or group of strata having been thus determined, the details of their mode of 

 occurrence, their relative abuudauce, and the facilities which may exist in each 

 separate district for making them economically available must, after the prelim- 

 inary general work has been done, be the object of more special and detailed 

 examinations. It is not, however, the business of a geological surveying corps 

 to act, to any considerable extent, as a prospecting party ; to do this, would 

 require that we should confine our operations to a very limited area ; the labors 

 of the whole corps for an entire season would not suffice to thoroughly prospect 

 more than a few huudred square miles in a very rich mineral region, and we 

 should have often to engage in expensive mining operations to decide what was 

 really of permanent value. It is our task, rather, to limit the field of research, 

 and to show to others where their labors will be best bestowed, preventing fool- 

 ish expenditures of time and money in searching for what our general geologi- 

 cal investigations have determined not to exist in sufficient quantity, in certain 

 formations, to be worth working. Especially in the first years of our work, in 

 a State of such an immense area as California, our labors have more the char- 

 acter of a geological reconnoissance than of a detailed survey. 



Already, however, during the progress of our work, a large amount of inform- 

 ation has been collected in reo-ard to the mode of occurrence and abundance of 

 the useful ores and minerals of this State and the adjoining Territories. The 

 principal deposits of coal have been carefully examined, and their geological 

 position ascertained. Most of the important quartz mines of the State have 

 been visited by Mr. Ashburner, and a large amount of information has been 

 collected by him, preparatory to an elaborate investigation and report on this 



