ns were
passable only when the weather was hot.

The floor of the valley was silt, sand and gravel--they would find
nothing there. They set out on a circuit of the chasm's walls, following
along close to the base.

In many places the mile-high walls were without a single ledge to break
their vertical faces. When they came to the first such place they saw
that the ground near the base was riddled with queer little pits, like
tiny craters of the moon. As they looked there was a crack like a cannon
shot and the ground beside them erupted into an explosion of sand and
gravel. When the dust had cleared away there was a new crater where none
had been before.

Humbolt wiped the blood from his face where a flying fragment had cut it
and said, "The heat of the sun loosens rocks up on the rim. When one
falls a mile in a one point five gravity, it's traveling like a meteor."

They went on, through the danger zone. As with the peril of the chasm's
heat, there was no choice. Only by observing the material that littered
the base of the cliffs could they know what minerals, if any, might be
above them.

On the fifteenth day they saw the red-stained stratum. Humbolt quickened
his pace, hurrying forward in advance of Barber. The stratum was too
high up on the wall to be reached but it was not necessary to examine it
in place--the base of the cliff was piled thick with fragments from it.

He felt the first touch of discouragement as he looked at them. They
were a sandstone, light in weight. The iron present was only what the
Dunbar Expedition had thought it to be; a mere discoloration.

They made their way slowly along the foot of the cliff, examining piece
after piece in the hope of finding something more than iron stains.
There was no variation, however, and a mile farther on they came to the
end of the red stratum. Beyond that point the rocks were gray, without a
vestige of iron.

"So that," Barber said, looking back the way they had come, "is what we
were going to build a ship out of--iron stains!"

Humbolt did not answer. For him it was more than a disappointment. It
was the death of a dream he had held since the year he was nine and had
heard that the Dunbar Expedition had seen iron-stained rock in a deep
chasm--the only iron-stained rock on the face of Ragnarok. Surely, he
had thought, there would be enough iron there to build a small ship. For
eleven years he had worked toward the day when he would find it. Now, he
h