back. Just then a great boulder, weighing many tons, struck the rock
just above their heads, then bounded off into the river, which it
struck with a mighty splash. The contact with the rocks sent off a
shower of sparks, a perfect rain of them.

"I---I guess I need a guardian," said the lad rather weakly.

"Yes, you probably would have been killed by the smaller pieces that
broke off," answered Nance. "Be content to stay where you are."

"How long have we got to stay cooped up in this half cave?" demanded
Stacy.

"All night, maybe," answered Dad.

"Good night!" said the fat boy, Slipping down until he had assumed a
sitting posture. He lay down and was asleep in a short time. Stacy
woke with a start when another giant rock smote the wall just above
their cave, exploding into thousands of pieces from the violent contact.

"Stop that noise! How do you suppose a fellow's going to sleep
when-----"

Stacy struggled slowly to his feet when he saw the drawn faces of his
companions.

"Was that another of them?" he asked hesitatingly.

"Yes," answered Tad, with a nod. "It is grand, but terrible."