emain unseen. He went forward cautiously.

Rocky walls; a floor of sand where his feet left no mark. He was
watching ahead and above him. His gun was ready in his hand; he did
not propose to be ambushed. He moved with never a sound.

The silence persisted; no living thing other than himself lent any
flicker of motion to the scene. Not even a lizard could hope for
existence amid these dead and barren heights. He was alone--the
certainty of it had driven deeply into his mind before the canyon end
was reached. And, desert man though he was and accustomed to traveling
the waste places of the earth, Rawson learned a new meaning and depth
of solitude.

Here was no voiceless companionship of trees or brush or cactus; no
little living things scuttled across the rocks--he was alone, the only
speck of life in a place where life seemed forbidden.

So sure of this was he that he stepped boldly from the canyon's end.
He knew before he looked that he would see only more of the same
desolation. And his mind was filled equally with anger and
disappointment.

* * * * *

Something was opposing him! Something had come into their camp--had
killed old Riley. And he, Rawson, had been so sure he would find
traces here that would allow him to give that opposing force a
name....

He stared out from the rocky cleft into a sun-blasted pit. Already
the rising sun was pouring its energy ever the jagged rim of bleak
rocks and down into the vast throat, choked and filled with ash.

It sloped gently from all sides, the gray-brown powder that had been
coughed from within the earth. It made a floor where Rawson could have
walked with safety. But he did not go on.

"Damn it!" he said with sudden savagery. "What a fool I was to think
of finding anyone here. Who would ever pick out a spot like this for a
base of operations?"

He stared angrily at the floor of ash, at the black, outcropping
masses of tufa. He was angry with himself, angry and baffled and tired
from his climb. Far down in the vast, shallow pit blazing sunlight
glinted from massive blocks whose sides were mirror-smooth. A whirl of
wind eddied there for a moment and lifted the dust into a vertical
gray column--the only sign of motion in the whole desolate scene.
Rawson turned and tramped back toward the long hot descent to the
floor of the Basin.

* * * * *

He tried to maintain an air of confidence before the men. H