"Flowering shrubs don't thrive in the subterranean caverns from which geysers spring," suggested Bradley.
Olson shook his head. "It beats me," he said.
"I've got it!" I exclaimed suddenly. "Look there!" And I pointed at the base of the cliff ahead of us, which the receding tide was gradually exposing to our view. They all looked, and all saw what I had seen—the top of a dark opening in the rock, through which water was pouring out into the sea. "It's the subterranean channel of an inland river," I cried. "It flows through a land covered with vegetation—and therefore a land upon which the sun shines. No subterranean caverns produce any order of plant life even remotely resembling what we have seen disgorged by this river. Beyond those cliffs lie fertile lands and fresh water—perhaps, game
