"The what?"
"The huge cleft which the story says once connected the upper world with this Abyss. And--"
"Is it open now," cried Stern, leaning sharply forward.
"Alas, no; but you hurry me too much, good friend. You understand, for a long time they lived the cave-life partly, and partly the upper life. And they increased a great deal in the hundred years that followed the explosion. But they never could go into the plains, for still the gas hung there, rising from a thousand wells--ten thousand, mayhap, all very deadly. And so they knew not if the rest of the world lived or died."
"And then?" queried the engineer. "Let's have it all in outline. What happened?"
"This, my son: that a still greater cold came upon the world, and the life of the open became impossible. There were now ten or twelve thousand alive; but they were losing their skill, their knowledge, everything. Only a few men still kept the wisdom of reading or writing, even. For life was a terrible fight. And they had to seek food now in the cave-lakes; that was all remaining.
"After that, another fifty or a hundred years, came the second great explosion. The ways were closed to the outer world. Nearly all died. What happened even the tradition does not tell. How many years the handful of people wandered I do not know. Neither do I know how they came here.
"The story says only eight or ten altogether reached this sea. It was much smaller then. The islands of the Lanskaarn, as we call them now, were then joined to the land here. Great changes have taken place. Verily, all is different! Everything was lost--language and arts, and even the look of the Folk.
"We became as you see us. The tradition itself was forgotten save by a few. Sometimes we increased, then came pestilences and famines, outbreaks of lava and hot mud and gases, and nearly all died. At one time only seven remained--"
"For all the world like the story of Pitcairn Island and the mutineers of the 'Bounty'!" interrupted the engineer. "Yes, yes--go on!"
"There is little more to tell. The tradition says there was once a place of records, where certain of the wisest men of our Folk placed all their lore to keep it; but even this place is lost. Only one family kept any knowledge of the English as a kind of inheritance and the single book went with that family--"
"But the Lanskaarn and the other peoples of the Abyss, where did they come from?" asked Stern eagerly.
The patriarch shook his head.