"El Pedregal"; a tract lying in its
south-western corner, contiguous to the Cerro de Ajusco, whose summit
rises over it to a height of 6,000 feet and 13,000 above the level of
the sea.

It is a field of lava vomited forth from Ajusco itself in ages long
past, which, as it cooled, became rent into fissures and honey-combed
with cavities of every conceivable shape. Spread over many square miles
of surface, it tenders this part of the valley almost impassable. No
wheeled vehicle can be taken across it; and even the Mexican horse and
mule--both sure-footed as goats--get through it with difficulty, and
only by one or two known paths. To the pedestrian it is a task; and
there are places into which he even cannot penetrate without scaling
cliffs and traversing chasms deep and dangerous. It bristles with
cactus, zuccas, and other forms of crystalline vegetation,
characteristic of a barren soil. But there are spots of great
fertility--hollows where the volcanic ashes were deposited--forming
little _oases_, into which the honest Indian finds his way for purposes
of cultivation. Others less honest seek refuge in its caves and
coverts, fugitives from justice and the gaols--not always criminals,
however, for within it the proscribed patriot and defeated soldier oft
find an asylum.

In the four individuals who had now entered there was all this variety,
if he who directed their movements was what the Condesa Almonte
described him. In any case, he appeared familiar with the place and its
ways, saying to Kearney, as they went on--

"No thanks to me for knowing all about the Pedregal. I was born on its
edge; when a boy bird-nested and trapped armadilloes all over it.
Twisted as this path is, it will take us to a spot where we needn't fear
any soldiers following us--not this night anyhow. To-morrow they may,
and welcome."

Their march was continued, but not without great difficulty, and much
exertion of their strength. They were forced to clamber over masses of
rock, and thread their way through thickets of cactus, whose spines,
sharp as needles, lacerated their skins. With the coupling-chains still
on, it was all the more difficult to avoid them.

Luckily, they had not far to go before arriving at the place where their
conductor deemed it safe to make a stop. About this there was nothing
particular, more than its being a hollow, where they could stand upright
without danger of being seen from any of the eminences aroun