556 SIERRA MADRE. Book III. 
Mexico on the western side of the Rio Grande, and the 
Mexican Californians give the same name to that chain of 
mountains which extends north of the plain of Los Angeles, 
from the Cerro de San Bernardino as far as the coast of the 
Pacific, and whose highest summit is the Cerro de San 
Antonio. 
With respect, however, to the great Sierra Madre, the 
western border of the Mexican plateau, — of which alone I 
am here speaking, — its structure possesses a peculiarity, 
which, although it cannot be called a rare orographic phe- 
nomenon, least of all in mountains extending along the 
edge of a plateau, yet has caused frequent errors in maps. 
Almost all the more important rivers which fall into the 
Californian Gulf take their rise on the high plains of the 
inner plateau, consequently upon the eastern side of the 
Sierra Madre. They force their way through the border- 
mountains in narrow fissures or gullies, and enter the coast- 
land at their lower western foot. I have already enlarged 
upon this fact with reference to the Rio de Papigochic, one 
of the two sources of the Rio Yaqui, when describing in a 
previous chapter my journey from Chihuahua to the Sierra 
Madre. The river flows for about sixty miles along the 
eastern foot of the mountain-chain, until it suddenly makes 
a right angle, rushes into a deep gully, and along this 
forces its way through the border-mountains. The road 
from Chihuahua to the rich mining-town of Batosegachic 
leads through a similar cross fissure, along one of the 
sources of the Rio del Fuerte. Geographers do not seem 
to know that the western border-mountains of the Mexican 
plateau do not form the watershed, but lie before the latter 
to the west, and, from attachment to an exploded theory, 
they have placed it further to the east ; thus bringing it 
nearer to the most western part of the Rocky Mountains 
