CLIMATE OF THE SANTA CATALINA MOUNTAINS. 81 
very dissimilar in their topographic location. In table 17 it will be 
seen that the winter minimum at Flagstaff, in northern central Arizona, 
was 21° below the minimum for Marshall Gulch, although Flagstaff is 
located 700 feet lower. This relation is similar to that which exists 
between the length of frostless season at Marshall Gulch and at Flag- 
staff, and is due to the facts mentioned in that connection on page 74. 
At the Fort Valley Experiment Station, located in the vicinity of 
Flagstaff and nearer to the San Francisco Peaks, the winter minimum 
was 4° lower than at Flagstaff. At Snowflake, on the extensive Mogol- 
lon Plateau, and at Fort Apache, in the cold-air drainage of one of the 
main forks of the Salt River, there were also minima which were 
respectively 9° and 3° lower than at Marshall Gulch, although these 
stations are respectively 2,000 and 2,400 feet lower than Marshall 
Gulch. Fort Huachuca is located at the base of the Huachuca Moun- 
tains in such a manner as to escape cold-air drainage from any of the 
large cafions of that range of mountains, and its absolute minimum was 
6° higher than that of Fort Apache, which is of approximately the same 
elevation. Chlarson’s Mill is situated in Frye Cafion in the Pinaleno 
(Graham) Mountains, surrounded by heavily forested slopes. Its loca- 
tion is analogous to that of Marshall Gulch, being similarly situated 
in an isolated desert mountain and surrounded by heavily forested 
slopes. The single monthly minimum available for Chlarson’s Mill 
is 15°, for a month in which the minimum at Tucson was 18°, while 
it was 7° for the Fort Valley Experiment Station, at almost the same 
elevation as Chlarson’s Mill. 
An inspection of the absolute minima for 1913-14, in table 17, will 
show that the same relations hold true between the several stations 
that have just been discussed. The winter minimum for Tucson, 26°, 
was much higher than in the preceding winter, and so was that for 
Marshall Gulch, 15.5°, although the absolute minimum in the new 
station on the fire tower at Mount Lemmon was 3°, and in the heavy 
timber on the north face of Mount Lemmon was 5°. 
The data just discussed amply bear out the statement that the lowest 
temperatures of winter are less severe on the Santa Catalinas than 
they are at the same elevation on the plateau of north-central Arizona, 
and even less severe than they are in many situations of lower altitude. 
The fragmentary records of earlier years at Chlarson’s Mill, which 
are not given here but are available in publications of the Weather 
Bureau, show that it is likewise favored by lower winter temperatures 
than are the plateau stations of the same elevation in Arizona. The 
length of the frostless season has just been shown to be less in the Santa 
Catalinas and in the Pinaleno Mountains than at Flagstaff. In short, 
the indications are very strong that all phases of winter temperature 
conditions are less severe on the small and isolated desert mountains 
than on the plateaus and highlands of the same elevations and of nearly 
