each side of us. The sky above appeared a mere strip of blue; and we
were surrounded by a gloom deeper than that of twilight. The torrent
roared and foamed at our feet; and the trail at times traversed through
the water.

There _was_ a trail, as we soon perceived; and, what was more
significant, one that had recently been travelled! Horses had been over
it; and in several places the rocky pebbles, that should otherwise have
been dry, were wet by the water that had dripped from their fetlocks. A
large troop of horses must have passed just before us. Had the dragoon
escort gone that way? More likely a party of mounted travellers
belonging to the train? And yet this did not strike us as being likely.
We were soon convinced that such was not the case. On riding forward,
we came upon a mud-deposit--at the mouth of one of the transverse
ravines--over which led the trail. The mud exhibited the _tracks_
distinctly and in a more significant light--they were _hoof-tracks_! We
saw that more than a hundred horses had passed up the defile; and not
one _shod_ animal among them! This fact was very significant. They
could not have been troop-horses? Nor yet those of white men? If
ridden, they must have been ridden by Indians? It did not follow that
they were ridden. We were travelling through a region frequented by the
_mustang_. Droves had been seen upon our route, at great distances off:
for these are the shyest and wildest of all animals. A _caballada_ may
have passed through the gorge, on their way to the upper valley? There
was nothing improbable in this. Although the plains are the favourite
habitat of the horse, the _mustang_ of Spanish America is half a
mountain animal; and often penetrates the most difficult passes--
climbing the declivities with hoof as sure as that of a chamois.

Had these horses been ridden? That was the point to be determined, and
how? The sign was not very intelligible, but sufficiently so for our
purpose. The little belt of mud-deposit was only disturbed by a single
line of tracts--crossing it directly from side to side. The animals had
traversed it in single file. Wild horses would have _crowded over it_--
some of them at least kicking out to one side or the other? This I
myself knew. The reasoning appeared conclusive. We had no longer a
doubt that a large party of Indians had gone up the gorge before us, and
not very long before us.

It now became a question of advance or