Marshall's discovery of gold in Sacramento valley was on January 24, 1848. But long before 1848 gold had been found in California near the Colorado River, near present San Diego County, around Los Angeles, and Monterey. The mineralogist, James D. Dana, of the Wilkes expedition in 1841, mentioned in his book on mineralogy that gold had been found in Sacramento valley. In his letter to Secretary Buchanan, Thomas O. Larkin wrote on May 4, 1846, that there was no doubt that gold, silver, and other minerals would be found in California. Report of Browne upon the Mineral Resources of the States and Territories West of the Rocky Mountains, November 24, 1866, in H. Ex. Doc. 29, 39 Cong., 2 Sess., 13-14 (1289).
