CHAPTER VII. 
ON THE GOLD OF CALIFOUNIA. 
(Extract from the IHbliolheque Vnivcrselle de Genive, Fevrier 1855.) 
Shortly after my last return to Europe, my friend, Professor Alphonse Favre of Geneva, 
requested me to send him some notes on the gold of California, as the geology of that country 
was very little known. The knowledge of the gold region was limited to the short Report of 
P. T. Tyson Upon the Geology of California-. Washington 1850; and a note just then published in the 
Quarterly Journal of the Geological Society of London, hy James S. Wilson, under the title: On the 
Gold Region of California, pag. 308, etc., vol. 10. Tyson made a rapid reconnaissance from Benicia 
to the American and Calaveras rivers in 1840, when the gold fever was at its height; and Wilson 
was himself a miner, who tried his luck for nearly three years in the southern district of the mines. 
On my arrival in California in March 1854, I rushed to the mines as soon as my duty with 
the expedition of Capt. Whipple was over , and in the course of a few days visited the northern 
district, at that time the richest and most productive in gold. Of course I do not give my notes 
as a minute description of what I saw during those few days , they are only a very rough sketch 
of the geology hordering the road from Marysville to Nevada-City, in the district of the northern 
mines. Since the publication of these notes in the Riblioihique Unkerselle de Gendee, the two excel- 
lent reports of Dr. John B. Trask entitled: Report on the Geology of the Coast Mountains and Part of the 
.Sierra Nevada, 1854 and 1855, have appeared, and they give a better idea of the geology of Cali- 
fornia in general , and especially of the mining district. 
The route from San Francisco, ascending the Sacramento river and then Feather river to 
Marysville, is constantly on the modern alluvium, with the exception of some localities near Hock 
Farm, the residence of the celebrated Captain John Sutter, the original discoverer of gold in 
California ; where drift or Quaternary rocks are found. Leaving Marysville and crossing the 
Sierra Nevada from west to east, we have the following section : modern alluvium till we reach 
the vicinity of Long Bar, Yuba river; two miles before reaching Long Bar dykes of trap are seen 
running from north to south, cropping out here and there, and then forming the whole country 
for a width of ten miles. This trap is a greenish feldspathic rock, containing lamellae of feldspar 
of the sixth system, and lamell® of white and sparry carbonate of lime are disseminated through 
the mass; there are also some grains of iron pyrites. This trap is very hard, irregular, and scaly 
when broken, sometimes serpentinous and contains no gold. Near the little town of Rough-and- 
Ready some veins of sienitic granite containing common feldspar or orthoclase, and hornblende 
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