"There's some trick about the thing, I know, but what it is gets me. Better stand back, all of you, in case it comes out all of a sudden," Mr. Kringle warned them.
All at once the boulder did come out, and it kept on coming.
"Look out!" bellowed the guide.
"Low bridge!" howled Stacy, hopping to one side and crouching against the rocks.
The guide had sprung nimbly to one side as well. The big rock had popped out like a pea from a pod. Instead of stopping, however, it continued to roll on toward the edge.
"Hug the rocks! She's going down!" shouted the guide.
Go down it did, with a crash that seemed to shake the mountain. Rolling to the edge of the shelf, it had toppled over, taking a large strip of shelving rock with it.
"Wow!" howled Chunky;
The other boys uttered no sound, though their faces were a little more pale than usual.
Kris Kringle stepped to the edge, peering over.