AMERICAN GEOLOGY DECADE OF 1840-1849. 427 



hig along great numbers of fresh-water snails of different species. Here we have 

 therefore, fresh-water shells and vegetation which is not marine accumulating under 

 salt water, for they sink after a while and must become buried in the mud of the 

 bottom, along with the remains of marine life. This floating vegetation illustrates a 

 theory with regard to the vegetation of the coal beds. 



The gold excitement of California in 1848-49 drew attention to a 



region the geology of which was practically unknown. Fremont's 



expedition to California and Oregon in 1843-44 was not accompanied 



by a geologist, and the few fossils collected were 



Tyson's Work in " tit tt ii ci -xt t 



California, described by James Hall, borne JNotes on the Cah- 



1849=1851. . J :' . . . 



forma Crold Kegion, six pages only, were given by 

 C. S. Lyman in the American Journal of Science for 1849, while 

 J. D. Dana had touched upon the subject during his return overland 

 after the disaster to the Wilkes Exploring Expedition. The main 

 gold-bearing area was, therefore, practically an unknown land. The 

 appearance in 1850 of Philip T. Tyson's Geology and Industrial 

 Resources of California was consequently important. Tyson seems 

 to have gone to California in 1849 as a private citizen, but so great 

 was the demand for information concerning the region that on his 

 return he made a report to Col. J. J. Abert, which was printed as a 

 Senate document the year following. 



In this report Tyson gave eight sections across the gold country, 

 two of which extended from the coast to the Sierras.. These were pub- 

 lished as mere outlines, showing the direction of the dip of the rocks, 

 but with no pretense to scale. He described the western flank of the 

 Sierras as consisting of a vast mass of metamorphic and hypogene 

 rocks, stretching from the Sacramento Valley to the axis of the moun- 

 tains. The metamorphic rocks, mainly slates, contained the veins of 

 auriferous quartz, through the breaking down of which had been 

 derived the gold found in the gravels of the ravines. 



Making all due allowance for Tyson's laudable desire to check the 

 wide and rapidly spreading excitement, bordering almost upon insan- 

 ity, caused by grossly exaggerated accounts of the richness of the 

 mines, still it would seem as if through overzealousness, or perhaps 

 through actual ignorance, he underestimated their value, both to his 

 own and others detriment. But it must be remembered that at that 

 time and in that remote region, deposits, either placer or in veins, 

 that could to-day be profitably worked, were valueless. He warned 

 prospective investors that the large bodies of gold-bearing quartz found 

 on the surface would if followed be found to be "'nothing more than 

 descending veins securely held between solid rocks, and that the cost 

 of mining such was enormous, whilst the chances were almost wholly 

 against their containing gold in proportion that would pay expenses. " 

 Indeed, Tyson regarded the prospect of a profitable mining of the 

 veins as ''altogether too remote and uncertain to be relied on." 



