"Look out for the landslide!" yelled Si, rushing into the open air. "Come out, or you'll be buried alive!"
The others heard the warning and started to leap from the hollow where they were working. But before they could do so the rumble burst forth like thunder, all but deafening them. Then down came some sand and small stones, all but burying the three. The mouth of the cavern was darkened, as a mass of dirt and rocks blocked it up completely.
"We are shut in!" spluttered Bob, as soon as he could speak.
The rumble stopped, but soon it started again, as another mass of dirt slid down the mountain-side, directly over the cavern. Then came a quiver as of an earthquake, and absolute quietness followed.
"Boys, are you hurt?" The question came from Maybe Dixon. He was up to his knees in loose dirt.
"I am all right," answered Mark.
"A small rock hit me on the shoulder, but the hurt doesn't count," returned Bob. "Where is Si?"
"I think he got out," said Mark. "But I am not certain."
"If he did get out maybe he is worse off than we are," said Maybe Dixon. "The landslide must have carried him down to the valley, or killed him."
For several minutes the three inside the cavern did not know what to do.