t were studded with settings of glass. This, however, was
easily accounted for; and I knew that the sparkling effect was produced
by plates of mica or selenite that entered into the composition of the
rock. I had seen large mountains that presented a similar appearance.
More than one such exist in the great American Saara, in whose
glittering cliffs, viewed from afar, may be found the origin of that
wild chimera, the _mountain of gold_.

Although neither a mountain of gold nor silver, the mound in question
was an object of rare interest. A very enchanted castle it did appear,
and it was difficult to assign its formation to nature alone. Human
agency, one could not help fancying, must have had something to do in
piling up a structure so regular and compact.

But he who has travelled over much of the earth's surface will have met
with many "freaks" of nature, exhibiting like appearance of design, in
her world of inorganic matter. It was, in fact, one of those
formations, of which many are met with in the plateaux-lands of America,
known in Spanish phraseology as _mesas_. This name is given to them in
allusion to the flat table-like tops, which distinguish them from other
elevated summits.

Sometimes one of these mesas is found hundreds of miles from any similar
eminence; more frequently a number of them stand near each other, like
truncated cones--the summits of all being on the same level, and often
covered with a vegetation differing materially from that of the
surrounding plains.

Geologists have affirmed that these table-tops are the ancient level of
the plains themselves; and that all around, and intervening between
them, has either sunk or submitted to the degradation of water!

It is a vague explanation, and scarcely satisfies the speculative mind.
The _mesa_ of Mexico is still a geological puzzle.

As we approached this singular object, I could not help regarding it
with a degree of curiosity. I had seen mesa heights before--in the
"mauvaise terre," upon the Missouri, in the Navajo country west of the
Rocky Mountains, and along the edges of the "Llano Estacado," which of
itself is a vast mesa.

The mound before us was peculiar, from its very regular form, and the
sparkling sheen of its cliffs. Its complete isolation, moreover, added
to the effect--for no other eminence appeared in sight. The low hills
that bordered the Rio Grande could barely be distinguished in the
distance.

On getting nearer