for ledge rock and listening for any sounds which
would tell him that he was nearing the other end of the cave.

In the meantime, unknown to the two chums, the boys remaining at the
gully were having a bit of excitement of their own, and were seriously
alarmed about the two in the cave.

The sound that Dick and Jack had heard in the cave was not thunder, as
Jack had suggested, but something entirely different.

When the boys had been in the cave a short time, there came a sudden
rustling on a part of the ledge Billy had aimed his camera at, and all
of a sudden a great boulder fell into the gully.

"Hello!" exclaimed Arthur. "That's bad. Who would have thought of it?
Jack and Dick are shut in there!"

A considerable mass of earth had been carried down with the boulder, and
now the entrance to the cave was completely filled by the rubbish.

"I am afraid they are shut in, Art," said Blaisdell seriously.

"Who would have thought of that?" cried Harry, going forward and looking
into the gully. "Certainly Jack did not, or he would not have gone in
there."

Blaisdell and three or four others stepped to the brink of the gully,
and looked down, as the dust began to settle.

"It's closed up all right," said Billy Manners, covering the aperture of
his pinhole camera.

"Do you mean the mouth of the cave or your picture box?" asked
Blaisdell. "You are a funny fellow, Billy."

"Both," said Billy tersely.

"I guess it is as far as the cave goes," remarked Jasper Sawyer. "Now
the question is how are we going to get the boys out?"

"H'm! we've got to take away that stuff, I suppose," said Harry. "It
won't be so hard getting down there, but there's a lot of stuff to get
rid of. Come on, boys, get down there and set to work."

"My! but there's a lot of this stuff!" exclaimed Sawyer, getting to
work. "I wonder if we can get rid of it before the boys get back? Do you
suppose they heard the noise and knew what it was?"

"How would they know?" asked Arthur, throwing aside a lot of stones and
earth. "The place is probably pretty big, or they would have been back
by this time."

There were four or five boys at work, but as Harry had remarked, there
was a lot of the earth and stones to remove, and they were more or less
in each other's way.

"We might call to them," suggested Jasper Sawyer at length. "If they are
not too far off they will hear us."

"That's all right," agreed Blaisdell, and he and the rest of the boys
sho