336 
CHARCOS DEL GRADO. 
Book II. 
for the night on the opposite side, on a grass-covered 
plain. The mountain peaks near the pass are bare, rocky, 
and in some places of grotesque form. On the right an open- 
ing passes through the rock from one side of the mountain 
to the other ; and one of our Mexican drivers told me that 
this part of the mountain is named, from this circumstance, 
Sierra de la Ventana, " Window Mountain." This name, 
however, did not appear to be generally used, for a 
gentleman, who had accompanied us from El Paso, called 
it Sierra de los Me'danos, or Sandhill Mountain. Behind 
this rose, as we approached it from the east, the needles 
and peaks of the Sierra de la Eancheria, which bears a 
great resemblance to the Sierra de los Organos. Farther 
on eastward, appears a similar mountain group named Sierra 
del Candelario. In the plain at the base of the former are 
the Charcos del Grado, pools surrounded by mimbre 1 
bushes. We reached these during the morning, and 
found fresh tracks of Indians, showing the need for 
redoubled caution. In the afternoon we distinguished, 
as we thought, the smoke of five fires in a southerly 
direction ; but the next day we discovered that they had 
been columns of dust caused by whirlwinds. I saw similar 
ones subsequently on a larger scale on the road to California, 
in the steppes of the state Sonora. The immoveability 
and duration of these whirlwinds are most curious and 
deceptive ; I have often watched them for hours on one 
spot. The phenomenon has much similarity with water- 
spouts. I have never heard whether they are attended 
with such danger in the North American steppes as was ex- 
perienced by the French troops on the southern side of the 
1 Mimbre is a beautiful shrub, which 
in northern Mexico, from Rio Grande 
to California, flourishes on the banks of 
intermitting streams. It is a bignonia- 
ceous plant, with pink and white blos- 
soms, and long, pendant, lanceolate 
leaves— a chilopsis. 
