80 VEGETATION OF A DESERT MOUNTAIN RANGE. 
Arizona at an elevation 700 feet lower than that of the 7,600-foot 
Station in Marshall Gulch. The extremely low temperatures at the 
Arizona Experiment Station and the office of the Desert Laboratory, 
as contrasted with the minimum temperature of 17° at the Desert 
Tassie 16.—Absolute minimum temperatures of two winters at stations in the Santa Catalina 
Mountains and at Tucson. 
Station. Location of station. 1912-1913. 1913-1914 
Arizona Experiment Station | Near bottom of Santa Cruz Valley. 6 26 
Office of Desert Laboratory | Edge of flood-plain of Santa Cruz 
Walleye asco eves actus ssc Wis ares eo 1 22 
Desert Laboratory......... Slope of hill, 335 feet above Santa 
Cruz Valley...............00- 17 29 
4,000 feet.............606- Ridge, in Lower Desert Region.... 13 27 
5,000: Rix ne aa swtawretan eaes Slope, 125 feet above floor of Soldier 
Cahion vsioices 4 elds a news ee. suwince.c 18 
6,000 Vis c2nsscicoenie eens Floor of Soldier Cafion, in Lower 
Hineinialsi:6. esse vacua vacant be eee we 18 
C000 Rese ee Siesta vee es Ridge in Upper Encinal.......... —6 18 
GB O00! Vie sies denies erceeess Floor of Bear Cafion............. as 6 
1000 oocice son ainrein te wxepere eek Ridge, north rim of Bear Cafion, in 
Pine Forest..........200c8e0. 5 12 
7,000 scsinedsaanereee canvas Bottom of Marshall Gulch, in Fir 
FOr eats sis siie.o.sieoacere acs ecie dsaee a —2 15.5 
8,000 ssi hess acnaancu toes Ridge, north rim of Marshall Gulch, 
Pine Forest............200005 5 
9,000 54.32 sy untowebnawenyes Northslope, below summit of Mount 
Lemmon in heavy Fir Forest... . 5 
OD kinds a cue Caner Ree Top of fire-tower on summit of 
Mount Lemmon.............. 3 
Laboratory, are to be accounted for through the operation of cold-air 
drainage. On the coldest night in January 1913 there was a difference 
of only 3° between the temperatures of the Santa Cruz Valley and 
Marshall Gulch, 5,400 vertical feet apart. It is desired here not so 
Tasie 17.—Absolute minimum temperatures of winter months for two winters at selected 
stations in Arizona, together with the absolute winter minima at 7,600 feet in the Santa 
Catalina Mountains. 
Station. 1912-1913. 1913-1914. 
Dec. | Jan. | Feb. | Dec. | Jan. | Feb. 
Santa Catalinas, 7,600 feet... 0... 0... cc cece ee feee ees me DE ha cieailecmansare 15.5]...... 
Tucson, 2,390 feet...... 0... ccc cece cae u ees 18 6 28 28 26 26 
Chlarson’s Mill, 7,200 feet...............0000- LB “iesigendicsiny vals cwiealaaaesralionsaas 
Flagstaff, 6,907 feet. .......... ccc ee ecw eee 0 |-23 |-7 |J-6 |—1 2 
Fort Valley Experiment Station, 7,300 feet..... — 7 |-27 |~-14 |-17 |-13 |-4 
Fort Apache, 5,200 feet............... ee eeee —2 |—5 5 3 |-1 14 
Fort Huachuca, 5,100 feet............. ce ceeee 21 1 21 26 23 29 
Snowflake, 5,644 feet... 2... cc cee eee e cece eens —-4 |-8 |-11 10 7 9 
much to lay emphasis on the exceptional coldness of the Santa Cruz 
valley, but on the exceptional warmness of the summit of the Santa 
Catalinas, as contrasted with similar elevations in Arizona which are 
