318 GEOLOGICAL REMAEKS. Book IT. 
rocks of the mountains, gave the scene an entirely new 
and striking character. Stags, hares, rabbits, and flocks 
of cranes, enlivened this wilderness, over which we pur- 
sued our way undisturbed for thirty miles, until we reached 
the lagoon, where we encamped for the night. 
This, as well as a smaller lagoon, a few miles further 
south, contains water for about three months in the year, 
collected during the rains. Both have neither an inlet nor 
an outlet. Immense flocks of ducks covered their surface, 
whilst hundreds of gigantic grey cranes were stalking 
about in the long grass on the shores. These birds were 
very shy, and would not let us come within shot. In the 
night I heard the rushing sound of flocks of cranes, 
geese, and ducks, over our heads ; they flew in a westerly 
direction across the desert, toward the Rio Grande. 
We halted the next day, for our noontide rest, at the 
second lagoon. All around rose barren, steep, and gro- 
tesque mountains, in single groups or isolated chains, on 
the borders of the prairie. The terrace stretches between 
them to the north, south and west, down to the Rio Grande, 
while to the east a communication with the table-lands on 
the Pecos exists over the mountain-passes between the 
Sierra de los Jumanes, the Sierra del Caballo, and other 
mountain chains. The rain in the afternoon prevented our 
reaching the so-called Aleman, a place we had fixed upon 
for our night encampment, from the water found there. 
The night cleared up, and the next morning the ground 
was covered with hoar-frost. 
Pursuing our journey, we came to a range of hills, 
stretching directly across the plain. The soil was com- 
posed of red clay, with pebbles and fragments of lime- 
stone, ferruginous sandstone, flint, hornstone, carniola, 
jasper, quartz, and silicified wood. The Larrea Mexicana 
