(Written by Colonel J.C. Fremont in 1847 (and updated in 1852) about his explorations and observations of California during the Gold Rush.)
Gold is also believed to exist on the eastern slope of the Sierra Nevada; and when at the mines, I was informed by an intelligent Mormon, that it had been found near the Great Salt lake by some of his fraternity. Nearly all the Mormons are leaving California to go to the Salt lake, and this they surely would not do unless they were sure of finding gold there in the same abundance as they now do on the Sacramento.
The gold "placer" near the mission of San Fernando has long been known, but has been little wrought for want of water. This is a spur which puts off from the Sierra Nevada, (see Fremont's map,) the same in which the present mines occur. There is, therefore, every reason to believe, that in the intervening spaces of 500 miles, (entirely unexplored,) there must be many hidden and rich deposits. The "placer" gold is now substituted as the currency of this country; in trade it passes freely at $16 per ounce; as an article of commerce its value is not yet fixed. The only purchase I made was of the specimen No. 7, which I got of Mr. Neligh at $12 the ounce. That is about the present cash value in the country, although it has been sold for less. The great demand for goods and provisions made by sudden development of wealth, has increased the amount of commerce at San Francisco very much, and it will continue to increase.