ce. Here, if it were not for the walls of rock rising on every
hand, we might imagine ourselves upon one of the desert plains
of Arizona.

[Illustration: FIG. 5.--CLIFFS ON THE TRAIL INTO THE GRAND CANON]

New views open at every turn in the trail, as it winds along the
narrow shelves of rock with precipitous walls above and below.
Now it zigzags back and forth down a gentle slope, but is soon
stopped by another precipice. In one place, to escape a rocky point,
the trail has been carried around the face of a cliff on a sort
of shelf made of logs. It then passes through a crevice formed by
the splitting away of a huge piece of the wall. In many places the
grade is so steep that the trail is made practically a stairway,
for the steps are necessary to keep animals from slipping.

Step by step we descend until the slope becomes more gentle and
a sort of terrace is reached, where men are at work developing a
copper mine. Everything needed for the mine is carried down packed
upon the backs of sure-footed burros. Even the water has to be
brought in kegs from a little spring still deeper in the canon.

The trail leaves the mine and winds down past another cliff, until,
when more than three thousand feet from the top of the plateau,
we find water for the first time. The little springs issue from
the sandstone, and their limited supply of water is soon drunk
up by the thirsty sands.

As far as the water flows it forms a little oasis upon the barren
slope. Along the course of the streams are little patches of green
grass, flowers, and bushes. Birds flit about, and there are tracks
of small animals in the mud. Evidently the water is as great an
attraction to them as it is to us. If a well were dug in the plateau
above, we can understand now how deep it would have to be in order
to reach water. A well three-fourths of a mile deep would be a
difficult one to pump.

We are now in the bottom of the main canon, but deeper still is
the last and inner gorge, through which the Colorado is flowing.
For thousands of centuries the river has been sawing its way down
into the earth. The precipitous cliffs which we have passed are
formed of hard sandstone or limestone. The more gentle slopes consist
of softer shales. Now the river has cut through them all and has
reached the very heart of the earth, the solid granite.

[Illustration: FIG. 6.--THE INNER GORGE OF THE GRAND CANON OF THE
COLORADO]

This inner gorge has almost vertical wal