n Garden,
another plateau rich with foliage, green grass and a riot of flowers.
It was like looking into a bit of the tropics.

"Here is the worst piece of trail we have yet found," called Nance.
"Go carefully," he directed when they reached the "blue lime." For the
next few minutes, until they had passed over this most dangerous portion,
little was said. The riders were too busy watching out for their own
safety, the Professor, examining the different strata of rocks that so
appeal to the geologist. He was entranced with what he beheld about
him. Professor Zepplin had no time in which to enjoy being nervous.

From there on to the Garden they rode more at ease in the "Boulder Bed,"
where lay large blocks of rock of many shapes and sizes that had rolled
from some upper strata. Small shrubs and plants grew on every hand,
many-hued lizards and inquisitive swifts darted across the trail, acting
as if they resented the intrusion.

Chunky regarded the lizards with disapproving eyes. But his thoughts
were interrupted by the voice of the guide pointing out the Temple of
Isis that looks down six thousand feet into the dark depths of the
inner abyss, surrounded by innumerable smaller buttes. The wonderful
colorings of the rocks did not suffer by closer inspection; in fact,
the colors appeared to be even brighter than when viewed from the rim
a few thousand feet above them.

Indian Garden was a delight. They wanted to tarry there, but were
allowed to do so only long enough to permit horses and riders to
refresh themselves with the cold water that trickled down through the
canals from the springs far above.

Reaching the end of Angel Plateau they gazed down a sheer descent of
twelve hundred feet into the black depths of the inner gorge, where
flowed the Colorado with a sullen roar that now was borne plainly to
their ears.

"It sounds as I have heard the rapids at Niagara do," declared Chunky
somewhat ambiguously.

"All off!" called the guide.

"What's off?" demanded Chunky.

"Dismount."

"Is this as far as we go?" questioned Tad.

"It is as far as we go on the pintos. We have to climb down the rest
of the way, and it's a climb for your life."

The boys gazed down the wall to the river gorge. The prospect did not
look very inviting.

"I guess maybe I'd better stay here and mind the 'tangs'," suggested
Stacy, a remark that brought smiles to the faces of the other boys.

"No, you'd be falling off if we lef