(Written by Colonel J.C. Fremont in 1847 (and updated in 1852) about his explorations and observations of California during the Gold Rush.)
The country on either side of Weber's creek is much broken up by hills, and is intersected in every direction by small streams or ravines, which contain more or less gold. Those that have been worked are barely scratched; and although thousands of ounces have been carried away, I do not consider that a serious impression has been made upon the whole. Every day was developing new and richer deposits; and the only impression seemed to be, that the metal would be found in such abundance as seriously to depreciate in value.
On the 8th of July I returned to the lower mines, and on the following day to Sutter's, where, on the 19th. I was making preparations for a visit to the Feather, Yubah, and Bear rivers, when I received a letter from Commander A. R. Long, United States Navy, who had just arrived at San Francisco from Mazatlan, with a crew for the sloop-of-war Warren, with orders to take that vessel to the squadron at La Paz. Capt. Long wrote to me that the Mexican Congress had adjourned without ratifying the treaty of peace, that he had letters from Commodore Jones, and that his orders were to sail with the Warren on or before the 20th of July. In consequence of this I determined to return to Monterey, and accordingly arrived here on the 17th of July. Before leaving Sutter's I satisfied myself that gold existed in the bed of the Feather river, in the Yubah and Bear, and in many of the smaller streams that lie between the latter and the American fork; also that it had been found in the Cosummes to the south of the American fork. In each of these streams, the gold is found in small scales, whereas in the intervening mountains it occurs in coarser lumps.