Bottom there was none--nothing save dull purple haze, shifting vapors, and an unearthly dim light which seemed to radiate upward as though the sun's rays, reflected, were striving to beat up again.
“There must be miles and miles of air below us,” said Stern, “to account for this curious light-effect. Air, of course, will eventually cut off the vision. Given a sufficiently thick layer, say a few hundred miles, it couldn't be seen through. So if there is a bottom to this place, be it one hundred or even five hundred miles down, of course we couldn't see it. All we could see would be the air, which would give this sort of blue effect.”
“Yes; but in that case how can we see the sun, or the moon, or stars?”
“Light from above only has to pierce forty or fifty miles of really dense air. Above that height it's excessively rarified. While down below earth-level, of course, it would get more and more dense all the time, till at the bottom of a five-hundred-mile drop the density and pressure would be tremendous.”
Beatrice made no answer. The spectacle she was gazing at filled her with solemn thoughts. Jagged, rent and riven, the rock extended downward. Here vast and broken ledges ran along its flanks--red, yellow, black, all seared and burned and vitrified as by the fire of Hell; there huge masses, up-piled, seemed about to fall into the abyss.
A quarter-mile to southward, a rivulet had found its way over a projecting ledge. Spraying and silvery it fell, till, dissipated by the up-draft from the abyss, it dissolved in mist.
The ledge on which they were lying extended downward perhaps three hundred yards, then sloped backward, leaving sheer empty space beneath them. They seemed to be poised in mid-heaven. It was totally unlike the sensation on a mountain-top, or even floating among the clouds; for a moment it seemed to Stern that he was looking up toward an unfathomable, infinite dome above him.
He shuddered, despite his cool and scientific spirit of observation.
“Some chemical action going on somewhere down there,” said he, half to divert his own attention from his thoughts. “Smell that sulphur? If this place wasn't once the scene of volcanic activities, I'm no judge!”
A moderate yet very steady wind blew upward from the chasm, freighted with a scent of sulphur and some other substance new to Stern.