The rock hauling went faster even with the rays of the single flashlight. They took turns climbing the slide and throwing rocks down. The boy taking a turn at the bottom moved them out of the way.
"Watch it!" Rick yelled suddenly, and jumped away from a slide of rock. Scotty, who was back in the tunnel disposing of a big rock, asked anxiously, "Are you hurt?"
"No. Hand me that light, will you?"
Scotty carried the light to where Rick waited. Rick took it and shone it upward to where the slide had come from. He whistled. There was solid ceiling, but it was a yard higher than the rest of the tunnel ceiling.
He calculated quickly. "If this is typical, we have rock three feet thick, ten feet wide, and twenty feet long piled up in front of us. That makes six hundred cubic feet of rock."
"But it can't be typical," Scotty disagreed. "If three feet had fallen uniformly, it wouldn't have filled the tunnel. It must be much thicker right over the broken timbers."
"Not a very cheerful prospect, is it?" Rick had a vision of yards of rock ahead.
"I've seen happier prospects. But what can we do? Keep plugging is all, and hope it doesn't take long for Dr. Miller to locate us."
Rick looked at his watch. "No chance of that yet. It isn't even suppertime. It may be morning before Dr. Miller gets really worried."
Scotty chuckled grimly. "Our own reputation for being able to take care of ourselves is not helping us, either."