208 BOTANICAL GAZETTE [SEPTEMBER 
the Arroyo Blanco, or Whitewater, a strong stream which is soon 
lost in the sands of the Colorado Desert. 
The Santa Ana River carries the seaward drainage, and has 
an airline course of 85 miles (136*™), in a southwest direction, 
to the ocean, which, it is said, its waters have been known to 
reach in high floods. In ordinary stages it sinks soon after dis- 
emboguing from the mountains, and reappearing after ten miles 
(16*™) carries more or less water nearly to Santa Ana. 
San Jacinto Mountain gives rise to a stream bearing the same 
name, which follows a southwest course to Elsinore Lake. Its 
channel, however, is only intermittently supplied with surface 
water. The Santa Margarita, the San Luis Rey, the Sweetwater, 
and some lesser streams, drain the mountains of San Diego 
county, and have a character similar to those already described. 
The Colorado River, which touches the border of the state, 
does not receive from it a single tributary, great or small; but 
an abandoned channel, the so-called New River, carries the 
waters of the Colorado, in times of great floods, into the south- 
eastern part of the desert and to the Salton Sea. 
GEOLOGICAL FORMATIONS. 
The great mountain axis consists principally of granitic forma- 
tions, and such is the prevailing character of the subordinate 
ranges. There are occasional outcroppings of limestones, but 
always of limited area. A range of Tertiary hills, conglomerates, 
sandstones and shales, beginning near Pasadena, stretches to the 
Santa Ana River, where it is divided by the granites of the 
Temescal Mountains, a narrow arm continuing along their north- 
eastern base, while a wider one (10-18 miles, 16-29*™) turns 
toward the coast, which it reaches at San Juan, and follows it 
thence to the Mexican boundary. A less important Tertiary 
formation skirts the southern base of the San Bernardino Moun- 
tains from Santa Ana Cafion to the Whitewater, occupying an 
area of 30 miles (48*™) in length by 1 to 5 miles (1.6-8*") in 
width. The same formation also appears in the Palos Verdes 
hills, and on the islands off the coast. 
The San Fernando Plains, the wide expanse of fertile country 
