AGRICULTURE AND SOILS OF CALIFORNIA. 479 
It has been suggested that a study of the growth-rings of the ancient 
Redwoods and Sequoias might lead to the recognition of the laws gov- 
erning the seasons through past ages; it being probable that the dry - 
years would be represented by a smaller growth than the wet ones. 
Unfortunately, it appears that in California, as well as in other countries 
where there is no well-defined season of rest for vegetation, the forma- 
tion of several growth-rings within the year is of frequent occurrence, 
so that even the estimate of the age of the great trees is thereby mate- 
rially vitiated. I have seen on the face of a redwood plank, 8 feet wide, 
groups of three, seven, twelve, and even thirty closely contiguous 
rings, occupying spaces but little larger than the intervals between two 
rings elsewhere, making it appear clearly that the unraveling of their 
record requires more than mere counting and measuring. But whatever 
may be the precise period in general, the fact that the average rainfall 
in so many regions nearly approaches the minimum required for any 
crop, gives exceptional importance to the minor, or annual, as weil as 
local variations of its amount and distribution. It thus happens that 
in each region experience has shown a. certain average expectation of 
successes and failures of unirrigated crops, which is taken into account 
by the farmer in his calculations. It is not, of course, easy to obtain 
perfectly impartial figures in this regard, the more as each valley may 
differ from its neighbor, and differences of crops, cultivation, and soil 
come in for a large share of influence. Besides, the shortness of the rain- 
fall during one “season” may be materially supplemented, and fair crops 
made, when the preceding season has been one of abundant rain, it being 
popularly said that there is a chance for a crop whenever the moisture 
rising from below and that coming from above have met. This natu- 
rally happens much sooner in land kept tilled than in such as has been 
left to crack open—given free access to the hot, dry air of summer. In 
’ such soil, in the San Joaquin Plains, no perceptible moisture is to be 
found at depths of three, and even four, feet at the end of the dry season, 
while in deeply tilled land it may be reached at 12 or 15 inches. Again, 
a slow and gentle falling of .a small amount of water will do as much 
good as a larger amouni falling violently and largely draining into the 
streams; while, on the other hand, a few days’ prevalence of a dry 
“norther” may completely wipe out the effect of spring showers that 
otherwise would have turned the scale in favor of the producer. 
For the middle San Joaquin Valley, with from 9 to 10 inches of aver- 
age rainfall, the usual estimate for cereals is that about two full crops 
out of five will be made without irrigation, the proportion increasing 
toward the north and decreasing toward the south, until in the Mojave 
Desert, with only about 3 inches of rain, the chances of making a crop 
without irrigation are too remote to be considered. Since, however, the 
rainfall increases pretty regularly with the elevation, the slopes and 
valleys of the foot-hills of the Sierra will frequently bear crops when 
there is failure in the valley. On the seaward slope of the coast range, 
where the rainfall is considerably greater than at a corresponding height 
and latitude in the interior, the average proportion of successes to 
failures varies greatly with locality and soil. The summer fogs brought 
in regularly by the trade-winds, as well as the coolness of that season, 
serve to eke out largely a scanty rainfall wherever the coast winds have 
access. Thus Santa Barbara, with about 12 inches of rain, only claims 
at least two crops out of three. The country bordering on the Bay of 
San Francisco, six out of seven or eight, each of the tributary valleys 
differing in this respect; and one, that of Napa, with 30 to 34 inches on 
an average, claiias that crops never fail for want cf sufficient moisture. 
