The Pony Rider Boys in the Grand Canyon

A lava field stretched directly in front of them, barring the way. Its forbidding surface had been riven by the elements until it was a perfect chaos of black tumult. By the time the Pony Rider Boys had gotten over this rough stretch, they were ready to sit down and rest. Nance would not permit them to do so. He said they would have barely time to reach the crater before dark, as it was, and that they must make the best speed possible. No one grumbled except Stacy, but it was observed that he plodded along with the others, a few paces to the rear.