rn away.

For perhaps an hour after the near-catastrophe, the air was filled with
blinding snow,--not that from the skies, but that of the snow dust raised
by the slide.

The circle of the rising moon threw a silver glamor over the scene. "What
do you figure makes these 'quakes, anyway?" asked Long Lester.

"The boys have asked that too, and I can't give it to you all in a
breath. But I'll give you the story before we end this trip."

At the moment of the earthquake, Ace and Ted, immured on a lower level of
the cave, were following a subterranean river. They got well splashed by
the waves set up, and worse scared, but it was all over in a minute and
they were only a degree more uncomfortably damp than they had been
before. Suddenly Ted gave an exclamation. A crag of drip-rock had been
shaken from the roof, and there, imbedded in the limestone, lay the plain
footprint of--it might have been a giant!

The boys stared, marveling a moment, then Ted voiced his guess. The
fossil of some giant of prehistoric ages! "A fossil, all right," Ace
agreed. "But that isn't a human footprint, even if there had been men
that size. That was made by some animal! If we ever get out of here,
let's bring Norris and come back with picks and find out."

"Then I can quarry this fossil out and sell it?" ventured Ted.

"Right-o!" with a congratulatory slap that made Ted wince.

But the inky stream had once more become placid, and skirting the muddy
ledge alongside, they threaded their way through arches of varying height
till finally the roof was so low that they had to go on hands and knees.
Then the bank became so narrow that Ace slipped off into the unknown
depths. To his surprise, his feet touched bottom. Moreover, the water
was not so cold as he had imagined. (It was about the same temperature as
the air).

"Come on in, the water's fine!" he encouraged Ted. "Do you know, we could
swim this if we had to, and don't you think it must lead out?"

"Stands to reason. But how about our candles?"

"Hold 'em in your teeth. Haven't you ever seen any one smoke a cigarette
when he was in swimming? It's a stunt, but----"

"Ever tried it?"

"Sure. Have you?"

"No." And the deepening water soon proved that he could not keep his
candle going. But Ace managed it for a few strokes. Then they had to swim
in darkness. An increasing roar told them that they were nearing white
water, possibly the outlet, and just as the current from a branch stream