200 FIELD COLUMBIAN MusSEUM—GEOLOGY, VOL. II. 
The trunks of the trees were often blackened by fire, but the trees 
themselves rarely showed signs of injury from this cause. Oaks 
were interspersed among the pines, and these grew more abundant 
toward the west. In the open spaces grass grew abundantly, but 
deciduous bushes or trees were generally. few. Signs of animal 
life were’ not abundant. At night the barking of coyotes could 
be plainly heard, especially as the higher elevations were reached. 
Hunters from Durango and. other cities are accustomed to visit the 
region to procure deer and mountain lions, but neither were seen 
on the writer’s journey. 
By man the region is practically uninhabited. Three so-called 
ranches were passed, which employ from three to ten hands each, 
but their production is scanty, and their income seems to be derived 
chiefly from the sale of supplies to passing pack-trains. Small herds 
of cattle belonging to these or other ranches were occasionally encoun- 
tered, but the possibilities of the region for Steams purposes seemed 
to be practically unutilized. 
Pack-trains, going to Durango chiefly from Mazatlan, were passed 
at least as often as every day, and sometimes two or three in a day. 
The trains were usually small, numbering from three to fifty mules, 
and were laden with tropical fruits, corn, or other staples. Occa- 
sionally foot travelers making the same journey were also encoun- 
tered, their burden being in one case parrots and in another straw 
‘“sombreros.”’ 
Such rocks as could be observed in passing were plainly of igneous 
origin, tuffs being prominent among them. Occasionally chalce- 
donic and jasperized seams were noted, indicating a secondary infil- 
tration of siliceous waters. 
The steady upward trend of the plateau was made evident fe a 
change in vegetation and an increasing coolness of temperature. At 
the higher levels the climate is too cold for even the growing of wheat. 
Grass suitable for cattle grows in abundance, however, even at the 
highest part of the plateau. Mountain streams with clear waters 
were crossed at intervals, giving evidence, together with the abun- 
dant forests, that this part of the plateau is well watered. 
On the evening of the fifth day a group of rude buildings, known 
as the Ciudad ranch (Plate LVI.), was reached. This ranch derives 
its name from the fact that in its vicinity occurs an area of remark- 
able erosion forms, known locally as La Ciudad de Rocas (“The City 
of Rocks’). Although the area is not visible from the trail itself, 
it can be seen by going a short distance from the latter. Mr. Rich, 
at that time manager of the ranch, kindly guided me to some glimpses 
