“Where is the Canyon?” asked Tad in a low voice.

“Yonder,” said Dad, pointing to the north over an unbroken stretch of forest.  There in the dim distance lay the walls of the Grand Canyon, the stupendous expanse of the ramparts of the Canyon stretching as far as the eye could see.

“How far away are they?” asked Tad.

“More than forty miles,” answered Dad.  “You wait till we get to the edge.  You can’t tell anything about those buttes now.”

“What is a butte—–­how did they happen to be called that?” asked Walter.

“A butte is a butte,” answered the guide.

“A butte is a bump on the landscape,” interjected Stacy.

“A butte is a mound of earth or stone worn away by erosion,” answered the Professor, with an assurance that forbade any one to question the correctness of his statement.

“Yes, sir,” murmured the Pony Rider Boys.  “A wart on the hand of fair Nature, as it were,” added Chunky under his breath.

“Come, we must be on our way,” urged Dad.  “We want to make half the distance to the Canyon before night.  I reckon the pack train will have gone on.  We’ll have to live on what we have in our saddle bags till we catch up with the train, which I reckon we’ll do hard onto noon.”

No great effort was required to descend Sunset Mountain.  It was one long slide and roll.  The boys screamed with delight as they saw the dignified Professor coasting and taking headers down the cinder-covered mountain.

By this time the clothes of the explorers had become well dried out in the hot sun.  When they reached the camp they found that the pack train had long since broken camp and gone on.

“Where are the ponies?” cried Walter, looking about.

“I’ll get them,” answered Dad, circling the camp a few times to pick up the trail.

It will be remembered that the animals had been hobbled on the previous afternoon and turned loose to graze.  Dad found the trail and was off on it running with head bent, reminding the boys of the actions of a hound.  While he was away Tad cooked breakfast, made coffee and the others showed their appreciation of his efforts by eating all that was placed before them and calling loudly for more.  Dad returned about an hour later, riding Silver Face, driving the other mustangs before him.  When the boys saw the stock coming in they shouted with merriment.  The mustangs had been hobbled by tying their fore feet together.  This made it necessary for the animals to hop like kangaroos.  The boys named them the kangaroos right then and there.

Tad had some hot coffee ready for Nance by the time Dad got back.  The guide forgot that he had declared against eating or drinking anything cooked by the Pony Rider Boys.  He did full justice to Tad’s cooking, while the rest of the boys stood around watching the guide eat, offering suggestions and remarks.  Dad took it all good-naturedly.  He would have plenty of opportunities to get back at them.  Dad was something of a joker himself, though this fact was suspected only by Tad Butler, who had noted the constantly recurring twinkle in the eyes of the guide.