on the farther side and a thicket of
low sage brush covered the rise in the land beyond.

Jim and Jack saw nothing moving in the sage brush or beyond it and there
was no one in sight. Their impression must have been a mistake, for the
only living thing in view was a flock of wild geese which flew over
their heads uttering their shrill clamor. Jim sat erect, silent and
watchful as an Indian, on the back of his equally motionless pony, his
hand shading his eyes.

Jack waited on her horse gazing at the quiet waters of Rainbow Creek.
Suddenly there came a low rumble inside the earth, like a note of
warning, and then the land began to rise in sandy billows as though wave
on wave were seeking some distant shore. The two horses with their
silent riders shook as with the ague; the face of Rainbow Lake shivered,
then her waters lashed the shores as though they had been parted
asunder, and a moment later receded and began to disappear. It was as if
old Father Neptune had deserted his home at the bottom of the sea to
play his mighty games in the shallow waters of Rainbow Creek. It seemed
as though he had blown a great blast through his sacred horn and caused
the water to spurt upward, then had drawn it slowly back into his horn
again.

The noise and the movement died away.

"Was it an earthquake, Jim?" Jacqueline managed to murmur, as soon as
she could get her breath. She had slipped quietly off her pony and was
patting it softly, for the broncho was terribly frightened at the
strangeness of his experience.

Jim nodded solemnly. "A human earthquake, I guess. Don't be alarmed, it
won't occur again, but get to cover quickly."

Jacqueline Ralston knew as well as though she had been a pioneer woman
trained to warfare with the Indians in the early days in the West, what
Jim's mysterious words, "get to cover," meant. She and Jim used to
play, long years before, that they were travelers across the plains,
being hunted down by bands of roving Indians. This was when Jack was a
small, bronze-haired tomboy, riding bare-back over the prairies,
swimming with her father in the clear, cold mountain streams, afraid of
nothing and of no one, the pride of every cowboy on Rainbow Ranch. Later
she had learned the value of hiding in ambush in stalking wild game.
But, even if Jack had not understood the importance of Jim's advice, she
had been trained to obey instantly the word of a superior officer in the
moment of action.

It was not an easy