For hours they rode steadily, skirting around the mountainside, forced higher and higher up the slopes by innumerable obstacles. Sometimes they crossed narrow ledges where a single misstep would have meant a frightful plunge down rough, jagged precipices.

"Humph! Here's where we seem stumped at last," remarked Jack, as the bronchos emerged from a belt of timber.

Just ahead, a reddish pinnacle of rock, almost as straight as a cathedral tower, and rising for hundreds of feet, presented a strangely impressive spectacle.

Bob Somers looked dubiously at the slope which slanted sharply from its base.

"A risky job getting around, fellows."

"A pippin," said Dick, with a deep breath.

"Well, we can do it," asserted Tim. "Come ahead."

The boys scarcely dared to look at the depths below when the sure-footed little bronchos began cautiously treading the steeply-inclined surface, sometimes sending small landslides sweeping down the slope. All uttered sighs of relief when they again reached safer ground.

About mid-afternoon Bob raised his hand.

"Listen, fellows!"