SOUTHERN PACIFIC LINES 185 
appears to be the remains of an old erosion surface, now deeply dis- 
sected, on which the Mount Lemmon highland rises as a rounded 
swell, probably a residual mound. The northwest corner shows 
evidence of later upbending of 1,000 feet or more. (W. M. Davis.) 
Rising to the south foot of the mountains is a steep slope of sand and 
gravel underlain by sandstones and conglomerates of supposed late 
Tertiary age revealed in the deeper canyons. The beds dip steeply 
away from the mountain front and in places are considerably faulted. 
The high Tanque Verde and Rincon Mountains, east of Tucson, 
also consist of gneiss. All these mountains are included in a national 
forest, for their higher parts sustain a growth of valuable timber : 
many live oaks and junipers occur from 4,500 to 6,000 feet, the yellow 
pine thrives between 6,000 and 8,000 feet, and there are small areas 
of fir and spruce above 8,000 feet. On the lower slopes sahuaros 
are numerous, notably on the west slope of the Tanque Verde Moun- 
tains, 15 miles east of Tucson, where the State University has reserved 
an area in which these interesting plants are especially abundant 
and large. 
TUCSON TO PICACHO, ARIZ. 
Tucson, the second city in size in Arizona, is the oldest settlement 
in the State and can boast of a colorful history. For many years 
it was a small, rough frontier town, preponderantly 
Tucson. % : " : 
Were: Mexican in population and appearance. Now it 
Population 32,508. is a well-ordered city containing the State University, 
New rns 14 with an enrollment of more than 3,000 students, 
es. 
many high-class hotels, clubs, and a large residential 
district of particular beauty and charm. These features, in addition 
to the mild, healthful climate, attract many new residents, as well 
as tourists. 
The State University, which is now accredited by the American 
Association of Universities, was built on ground donated by three 
leading gamblers of the city, and the first building was constructed 
before there was a high school in the Territory; during its first years 
students had to be taught the prerequisites to its freshman course. 
The university includes the Arizona Bureau of Mines, which is making 
investigations of the mineral resources of the State, and the Stewart 
Observatory for astronomical research. An important investigation 
conducted by Prof. A. E. Douglas has established a chronology 
of tree rings, which gives a key to the age of logs used in aboriginal 
houses and even to some that occur in petrified condition. There 
are at Tucson also the Desert Laboratory of the Carnegie Institution 
and a seismologic observatory of the United States Coast and Geo- 
detic Survey. 
152109°—33——13 
