hundreds of pounds; forcing their protesting legs to carry them fifty steps at a time, at the end of which they would stop to rest while their lungs labored to suck in the thin air in quick, panting breaths.
It would have been much easier to have gone around the mountain. But the Chasm was supposed to be like a huge cavity scooped out of the plateau beyond the mountain, rimmed with sheer cliffs a mile high. Only on the side next to the mountain was there a slope leading down into it.
They stopped for the night where the creek ended in a small spring. There the snow still clung to the canyon’s walls and there the canyon curved, offering them the promise of the summit just around the bend as it had been doing all day.
The sun was hot and bright the next morning as they made their slow way on again. The canyon straightened, the steep walls of it flattening out to make a pair of ragged shoulders with a saddle between them.
They climbed to the summit of the saddle and there, suddenly before them, was the other side of the world—and the Chasm.
Far below them was a plateau, stretching endlessly like the one they had left behind them. But the chasm dominated all else. It was a gigantic, sheer-walled valley, a hundred miles long by forty miles wide, sunk deep in the plateau with the tops of its mile-high walls level with the floor of the plateau. The mountain under them dropped swiftly away, sloping down and down to the level of the plateau and then on, down and down again, to the bottom of the chasm that was so deep its floor was half hidden by the morning shadows.
“My God!” Barber said. “It must be over three miles under us to the bottom, on the vertical. Ten miles of thirty-three percent grade—if we go down we’ll never get out again.”
“You can turn back here if you want to,” Humbolt said.
“Turn back?” Barber’s red whiskers seemed to bristle. “Who in hell said anything about turning back?”
“Nobody,” Humbolt said, smiling a little at Barber’s quick flash of anger. He studied the chasm, wishing that they could have some way of cutting the quartz crystals and making binoculars. It was a long way to look with the naked eye …
Here and there the chasm thrust out arms into the plateau. All the arms were short, however, and even at their heads the cliffs were vertical. The morning shadows prevented a clear view of much of the chasm and he could see no sign of the red-stained strata that they were searching for.
In the southwest corner of the chasm, far away and almost imperceptible, he saw a faint cloud rising up from the chasm’s floor. It was impossible to tell what it was and it faded away as he watched.
Barber saw it, too, and said, “It looked like smoke. Do you suppose there could be people—or some kind of intelligent things—living down there?”
“It might have been the vapor from hot springs, condensed by the cool morning air,” he said. “Whatever it was, we’ll look into it when we get there.”
The climb down the steep slope into the chasm was swifter than that up the canyon but no more pleasant. Carrying a heavy pack down such a grade exerted a torturous strain upon the backs of the legs.
The heat increased steadily as they descended. They reached the floor of the valley the next day and the noonday heat was so great that Humbolt wondered if they might not have trapped themselves into what the summer would soon transform into a monstrous oven where no life at all could exist. There could never be any choice, of course—the mountains 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 under 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.
