they would have plunged into the rocky floor
of a canyon a thousand feet below.

"Let's see if we can find a way down to the valley," he suggested. "If
we get anything to eat it will have to come from trees. This plateau
is barren of any form of vegetable matter."

They found a winding descent leading downward. It looked like a path
that had been worn by the passage of many feet.

"Someone's been here before us," he exclaimed. "The ground is too well
worn to be accidental."

"Look! Look!" pointed Nanette. Her face had become pale from the
excitement of her discovery. "What is it, Aaron?"

Carruthers bent forward to examine the strange footprint. It was
nearly two feet across and divided in the center, as if the animal
that made it had but two toes.

"From the size of the tracks and the length of the animal's stride, I
should say it was some form of an amphibious dinosaur long extinct in
our own world."

"Are they dangerous?"

"It all depends upon the species. Some of them are pure vegetarians;
others are carnivorous. The heavy tramping we heard during the night
evidently came from the beast who left these footprints."

* * * * *

They had come upon the footprints where the path made a turn, leading
into a dense growth of trees and underbrush. And as Carruthers knelt
beside the path he heard a rustle as of something moving directly
behind him. Wonderingly, he turned his head to trace the disturbance.
But the woods seemed empty. "Strange," he murmured. "Did you hear
something moving in back of us, Nan?"

Nan shook her head. "You don't think we're in any danger from these
beasts, do you?"

Carruthers said nothing for the moment. Instead, he looked sharply in
all directions and saw nothing. "Let's push on till we come to some
kind of a shelter. Perhaps we'll find people much like ourselves."

Down the path they hurried, glancing curiously right and left at
unknown flowers and trees. A bird with brilliant feathers skimmed
above their heads, uttering shrill cries. Other voices from the birds
and animals in the woods took up the cry. The woods grew denser as
they pushed into the unknown.

In the woods at their right a rodent squeaked as some larger animal
pounced upon it. Presently they came to a pool of water roughly
seventy feet across. While they knelt to quench their thirst they saw
two young deer eyeing them from the far side. Soft feet pattered
behind the kneeling couple.