34 RESOURCES OF CALIFORNIA. 
and the same difference is observed between Nevada and Ma 
rysville, which bear similar relations of distance and elevation 
to each other. . 
The statistics given in the preceding part of this section 
relative to the amount of rain-fall at San Francisco, are intend- 
ed to represent ordinary years, such as all those between 1847 
and 1860. But the winter of 186162 proved to be an ex- 
traordinary season, the amount of rain being double that which 
has fallen in any other winter since the American conquest. 
The average rain-fall during the winter months at San Fran- 
cisco is about 12 inches; whereas, between the 1st of Novem- 
ber, 1861, and the 1st of February, 1862, 37 inches fell in San 
Francisco, and during the same period 101 inches fell in So- 
nora, Tuolumne county. During the four months from the 1st 
of November, 1861, to the 28th of February, 1862, inclusve, 
45.53 inches of rain fell in San Francisco, viz.: 4.10 in Novem- 
ber; 9.54 in December; 24.36 in January; and 7.53 in Feb- 
ruary. This rain caused a great flood, which did much damage 
along most of the rivers, and especially in the Sacramento 
Basin, where Sacramento City, Stockton, Marysville, and nu- 
merous minor towns, were completely inundated, and the 
whole central part of the basin, including an area one hundred 
and fifty miles long and twenty miles wide, was converted 
into a great lake, which covered the land to a depth varying 
from two to ten feet for more than a month. The long dura- 
tion of the flood, its great height, and the vast damage which 
it did, will render it an epoch in the history of the state, and 
make it well worthy of study, especially so far as relates to 
the Sacramento Basin, where the most serious injury was done 
—that basin extending north and south from Mount Shasta to 
the Tejon Pass, a distance of four hundred and fifty miles; and 
east and west from the summit of the Coast Range to that of 
the Sierra Nevada, a distance of one hundred miles. These 
two ranges unite at the two ends of the basin, which has its 
outlet in the middle, where the Sacramento from the north and 
the San Joaquin from the south, having united their waters in 
