12 CHAPARRAL. 
While to a Californian this chaparral region may seem normal 
enough, a visitor from the Eastern States seems to be entering a new 
world. One thing to set it apart is the seasonal distribution of rain- 
fall. Over the chaparral region in southern California the scant 
rains occur during the winter months; there is little, if any, pre- 
cipitation in summer. At San Luis Obispo, in the northern portion 
of the chaparral region, only 2.91 per cent of the rainfall is in the 
summer; at Los Angeles, in the central portion, only 0.83 per cent; 
and at San Diego, in the southern portion, only 0.89 per cent. 
Other interesting geographic conditions beside the wet-winter, 
dry-summer climate exist in the area. We usually think of the moun- 
tain ranges of the United States as running north and south, but the 
largest and most important range in the chaparral region, the Sierra 
Madre, including the Sierras San Raphael, San Gabriel, and San 
Bernardino, trends almost due eastward from Point Conception. It 
is in these Sierras that the chaparral reaches its best development, 
both in the number and size of its species and in the density of its 
cover. The rain-bearing clouds coming from the west do not find 
this range an effective barrier, but move eastward through broad, low 
passes on either side. To the northward are the Sierras Nevada and 
Santa Lucia, and to the southward the San Jacinto, all of which have 
greater rainfall than the Sierra Madre. 
We usually think of springtime as the season when plants begin 
their growth and when deciduous trees and shrubs spread a new 
foliage, which remains green until autumn. In the chaparral area 
this is reversed, and the various species make most of their growth 
during the winter. Through the summer season the mountains are 
brown, and, from a distance, look lifeless. Immediately on the advent 
of the winter rains the whole country puts on a vesture of green, 
which remains all winter. 
There are other conditions which seem topsy-turvy. We think 
of high mountains as barren and snow covered at their summits; 
below this the timber line, with its stunted trees of the subalpine 
zone; descending farther, the forests in full possession of the slopes, 
and the trees increasing in size until, with the undergrowth, they 
form a heavy cover upon the coastal plain. In the chaparral region 
all this is reversed. The forests are on the high elevations. Below 
is the chaparral, or zone of dwarfed trees. Still farther down is the 
sagebrush country, the growth becoming thinner and thinner toward 
the bare sandy belt bordering the ocean. The lower zones, except in 
favored valleys, are arid, or at least semiarid. The rainfall increases 
with the altitude above the sea, approximating the rate of Lippin- 
cott’s formula, which is 0.6 inch for each 100 feet of rise. Along the 
coast the average annual rainfall is 13 inches. This is insufficient to 
support a forest, and in only a few cases is it enough for a scattering 
