“I certainly can,” Don answered. “Perhaps it comes from above!”
“No, sir! It is right down here in this angle—the opening, I mean! And it is a strong current of air, too, so it must come from some canyon to the west. The rocks are piled in here in all kinds of shape, anyway. When the Colorado bored down, it upset things and left lots of layers standing on end. Here! See that little opening? Well, there she blows! Little bit of a hole for so much wind.”
“Just like a campaign orator!” Don commented.
Clay looked at his friend reproachfully and crowded into the aperture, which was formed by two layers of rock, stacked up on end, as he had before expressed it, much farther apart at the bottom than at the top. The passage was about four feet in width, and not much more than that in height. The bottom was covered with a fine sand, laying in wrinkles, and showing the action of running water.
“You see,” Clay observed, pointing down, “this is a water channel at certain seasons of the year, so it must lead to some open place.”
“You’re never going in there!” shouted Don. “How do you know what kind of wild animals you’ll run against?”
“Of course I’m going in,” Clay replied. “For all we know, this hole leads to a parallel canyon which we can ascend to the vicinity of the motor boat. If we had our searchlights it would be a picnic.”
But their searchlights were on board the Rambler, and so it was anything but a picnic the boys had following the dark passage. The walls brushed their elbows at times, and occasionally they ran their heads full tilt against the roof of the cavern, but the floor, being at times the bottom of a torrent, was comparatively level, except that it mounted up at an angle of about twenty-five degrees.
The atmosphere was remarkably pure, for the cool wind which had attracted Clay’s attention to the opening, continued to sweep through the passage, but it was dark—wretchedly, miserably, uncannily dark, and the boys imagined many times that they heard the warning growls of wild animals or felt the touch of slimy reptiles. Twice they came to places where their progress seemed blocked, but these were only twists in the rock, and directly they found their way on again.
Presently, at his very feet, Clay heard the rush of water, and halted. The boys stood together for a time and listened. It was falling and not running water they heard. Somewhere in the interior of the mysterious passage, there was a waterfall.