fragment fitting exactly into its appointed place, the whole forming a
marvelous piece of natural mosaic that could only have been designed by
the Master Artist.

With the point of his pocket knife the Desert Rat pried loose one of
these sections of lava. Where it had been exposed to the sun on top it
was brown, but the under side was the original creamy white.

The mystery of the phantom trail was solved at last. In fact, not to
state a paradox, there had been no mystery at first--at least to the
Desert Rat. The moment he saw the bones he guessed the answer to that
weird puzzle.

The tracks were easily explained. When one walked on the surface of
this thin lava crust it broke beneath him and crumbled into dust. The
brown dust on top mingled with the underlying white, the blend of
colors on the whole forming a slate-colored patch with creamy edges,
marking the boundaries of the footprints; and here, in this horrible
canyon, where rains would never erode nor winds obliterate, the tracks
would show for years until the magic of the desert had again wrought
its spell on the landscape and the ghostly white tracks had faded and
blended again into the all-prevailing brown.

The Desert Rat was something of a geologist, and had he not been dying,
an extended examination of this weird formation would have interested
him greatly. But he had his message to leave to his loved ones, and
time pressed. In the joy and pride of his strength and youth he had
dared the desert. He had dreamed of a fortune, and this--this was to be
the awakening...