

Mineralogy and Geology. 417 



elly projections formed at the bendings of the streams, are often ex- 

 tremely rich in metal. A bar in the Rio de los Americanos, (at high 

 water an island,) about twenty-three miles above New Helvetia (now 

 called Sacramento) and on which some of the earliest explorations were 

 made, is of this character. But where the diluvium has remained un- 

 disturbed since the period of its deposition, I am confident no "allu- 

 vial" or "stream" gold has been, or will be discovered, except in con- 

 nection with it. It is evidently as much "part and parcel" of this 

 formation as its associated quartz, greenstone, hornblende, and other 

 pebbles, and whoever will explain the origin of the one, will at the 

 same time elucidate the origin of the other — for one and the same 

 agency unquestionably spread both of them over the surface of the 

 district. What the latest theory of geologists is to account for the dis- 

 persion of drift, I am too isolated from the scientific world to know. 

 Quartz is the only substance with which I have seen the gold intimately 

 united, and these compound lumps seem to show clearly that the orig- 

 inal matrix or veinstone of the metal was a dyke or bed of quartz 

 rock. And we have only to suppose, that when the quartz, with its 

 accompanying rocky strata, was broken up by natural agencies at some 

 former geological epoch, the interspersed or included veins of gold 

 were at the same time reduced to fragments, and these rough and an- 

 gular fragments subsequently broken and further comminuted and 

 rounded by mutual attrition, to account for the present form and ap- 

 pearance of the gold, and for its constituting a portion of the materials 

 of the drift. But whether these materials with their golden treasure, 

 now occupy the precise geographical position of their parent rocks, or 

 whether they have been transported by aqueous or glacial agencies or 

 both, from some neighboring or perhaps far distant locality, is a ques- 

 tion which future investigations into the geology and physical geogra- 

 phy of the region will better elucidate than the imperfect data at pres- 

 ent in my possession. I cannot avoid the fancy, however, in connec- 

 tion with the glacio-aqueous theory, that when the continent was wholly 

 or partially submerged, the materials of the diluvium, including the 

 gold, were transported by icebergs from their parent locality, and 

 when at length set free, left to assume their present position on what 

 was then the rocky and uneven bottom of the superincumbent ocean. 

 And we have only to imagine these freighted icebergs stranded by- 

 oceanic currents against the partially emerged range of the Sierra Ne- 

 vada, to account for the great longitudinal extension of the gold region 

 along the western slope of the mountains, while laterally it appears to 

 extend neither above nor below certain definite limits. 



The gold of different localities varies very much in size. That from 

 the banks and sandbars of the rivers, is generally in the form of small 

 flattened scales, and commonly it is found to be finer the lower down 

 you descend the stream. That taken from the bottoms of the dry ra- 

 vines, which every where abound in these mountains, and furnish out- 

 Jets for the torrents of the rainy season into the principal streams, is 

 mostly of larger size, and occurs both in small particb and also in 

 small lumps and irregular water-worn masses, from the size of wheat 

 kernels to pieces of several ounces or even pounds in weight. The 

 fine gold of these ravines is commonly less worn and flattened than 



