The rain had formed a long pool between the slanting rocks. He threw a chip into this pool and saw that it drifted slowly off between two scrub bushes growing partly under a shelving rock.
With the light he made an inspection of the locality, and a cry of surprise escaped him. Beyond the bushes was the opening to an irregular, but apparently large cavern.
The stream flowed along one side of the flooring to this opening.
"Must be some sort of an outlet beyond," he mused. "I'll try it and see," and in a moment more he was inside of the cavern and crawling along on hands and knees.
He had not far to go in this fashion. Twenty feet beyond the cavern became so large that he could stand up with ease. He flashed the light above his head.
"By Jove! a miniature Mammoth Cave of Kentucky!" burst from his lips.
On he went until a bend in the formation of the cavern was gained. Here the stream of water disappeared under a pile of loose stones, and the opening became less than six feet in height.
"Checked!" he muttered, and his face fell. It looked as if he would have to go back the way he had come.
Again he raised his light and gazed about him with more care than ever.
The loose rocks soon caught his attention, and, setting down the lantern, he began to pull away first at one and then another.