both sides by rugged impassable precipices. Vast masses of
shapeless rocks lie along the beds of these great clefts, and pools of
water appear at long intervals, while stunted cedars grow among the
rocks, or cling from the seams of the cliffs.

Such chasms, called "canons," can only be crossed, or even entered, at
certain points; and these passes are frequently a score of miles distant
from each other.

On the upper plain the surface is often a dead level for a hundred
miles, and as firm as a macadamised road. There are spots covered with
a turf of grass of the varieties known as gramma, buffalo, and mezquite;
and sometimes the traveller encounters a region where shallow ponds of
different sizes stud the plain--a few being permanent, and surrounded by
sedge. Most of these ponds are more or less brackish, some sulphurous,
and others perfectly salt. After heavy rains such aqueous deposits are
more numerous, and their waters sweeter; but rain seems to fall by
accident over this desolate region, and after long spells of drought the
greater number of these ponds disappear altogether.

Towards the southern end of the Llano Estacado the surface exhibits a
very singular phenomenon--a belt of sand-hills, nearly twenty miles in
breadth and full fifty in length, stretching north and south upon the
plain. These hills are of pure white sand, thrown up in ridges, and
sometimes in cones, to the height of a hundred feet, and without tree,
bush, or shrub, to break their soft outlines, or the uniformity of their
colour. But the greatest anomaly of this geological puzzle is, that
water-ponds are found in their very midst--even among their highest
ridges--and this water not occasional, as from rains, but lying in
"lagunas," with reeds, rushes, and _nymphae_ growing in them, to attest
that the water is permanent! The very last place where water might be
expected to make a lodgment.

Such formations of drift-sand are common upon the shores of the Mexican
Gulf, as well as on European coasts, and there their existence is easily
explained; but here, in the very heart of a continent, it cannot be
regarded as less than a singular phenomenon.

This sand-belt is passable at one or two points, but horses sink to the
knees at every step, and but for the water it would be a perilous
experiment to cross it.

Where is the Llano Estacado? Unroll your map of North America. You
will perceive a large river called the Canadian rising in the Ro