376 WATERSHED OF THE PACIFIC OCEAN. Book II. 
had been plundered and destroyed by the Apaches. On 
the other side of the pass we came to the plain of Cerro 
Prieto, which is only a continuation of the table-land ex- 
tending round the southern base of the mountain. Here, 
for the first time, we came upon a portion of the real 
system of the Sierra Madre — a long mountain-ridge covered 
with thick and lofty pine forests. This joins the plain at 
Cerro Prieto, and bounds on the south-west a small strip of 
the table-land, which, enclosed to the north-east by the 
Sierra de las Casas Coloradas and its offsets, imprisons a 
small stream belonging to the watershed system of the 
Pacific Ocean for full sixty miles in a north-westerly direc- 
tion between these mountains. A small lake, already 
named as the Laguna de Cerro Prieto, lies on the water- 
shed. The plain surrounding it is a real Alpine prairie, 
into which the lofty pine- forest of the Sierra Madre descends. 
The village of Cerro Prieto lies to the south-west of the 
lake ; we left them to the west of our route. The water 
and its shores were covered with flocks of geese and ducks. 
We went on in a north-westerly direction along the above- 
named narrow strip of table-land. This forms at first the 
base of the valley between these two mountain chains ; but 
gradually, as the bed of the stream washes deeper into the 
alluvial ground, broad terraces are formed, the surface of 
which belonged perhaps originally to the declivity towards 
the Gulf of Mexico, while the worn river bed exhibits the 
first lowering of the ground towards the Pacific Ocean. 
The small stream, rapidly augmented in size by the moun- 
tain torrents, forms one of the branches of Rio Yaqui of 
Sonora. 
We spent a wretched night of hunger and cold near 
some inhospitable houses, called los Ranchitos, or the Huts. 
Passing the buildings of the deserted Rancho del Rosario, 
