What puzzled the lads more than all else were the great leaping waves
that rose without apparent cause from spaces of comparatively calm
water. These upturning waves, the guide explained, were the terror of
explorers who sought to get through the Canyon in boats.

"Has any one ever accomplished it?" asked Tad.

"Yes; that intrepid explorer, Major J.W. Powell, made the trip in the
year 1869, one of the most thrilling voyages that man ever took. Several
of his men were lost; two who managed to escape below here were killed
by the Indians."

"I think I should like to try it," said Tad thoughtfully.

"You won't, if I have anything to say about the matter," replied Dad
shortly.

"No one would imagine, to gaze down on this stream from the rim, that
it was such a lively stretch of water," remarked the boy. "It doesn't
seem possible."

"Yes, if they had some of this water up on the plateau it would be
worth almost its weight in gold," declared Nance. "Water is what
Arizona needs and what it has precious little of. Speaking of the
danger of the river," continued Nance, "it isn't wholly the water, but
the traveling boulders."

"Traveling boulders!" exclaimed the boys.