"Don't say it!" Freddy begged. "Let's stop guessing and not break our hearts. Let's just walk. What's the matter? Can't you go faster than that?"

Dave grinned happily as the English youth increased his stride and went sailing into the lead. Just like old Freddy Farmer. Groans and gripes a bit, and then before you know it he's making you look like the one who's groaning and griping.

"Tough guy, huh?" Dave chuckled, and drew up on a level with Freddy's shoulder. "Maybe you want to sprint the rest of the way? Well, skip it, pal. This pace is fast enough for me. Boy! Only a couple of minutes more. And look, Freddy! It's like a regular cliff. Two cliffs, with a valley in between. Gosh! What do you know! A canyon cut into this darn flat desert."

"Think again, Dave," Freddy said with a smile. "Better still, turn around and take a look. I did. We've really been walking uphill, to the top of a plateau formation of ground. Those cliffs are the two sides of a crack that time has made in the plateau formation of ground. Just as unexplainable as why you suddenly come across an oasis with water and palm trees in the middle of a barren desert."

At Freddy's suggestion Dave turned around and looked back in the direction whence they had come. It was then he realized the truth of the English youth's words. Instead of standing on a flat, almost shapeless desert, they were actually standing near the crest of a long sloping hill. True, the slope was marked by countless sand dunes kicked up by the desert winds, but it was still easy to see that they were a good couple of hundred feet higher than they had been when they'd started out. To make sure it all wasn't just a trick his eyes and the desert sun were playing on him, he turned front again and looked at the brownish slash that marked the split in the plateau and formed the escarpment. The brownish slash in the desert was the highest piece of ground before his eyes. Beyond, he could see only Libyan sky and the brassy glare of the sun. That was so because he was actually looking uphill.

"Well, what do you know!" he exclaimed, and grinned at Freddy. "No wonder my legs feel ready to drop off. We've been plowing uphill and didn't know it."

"The desert is full of tricks," the English youth said with a shrug. "And all of them mean ones, too. Well, let's get on with it. Won't be long now."

It turned out to be longer than that, however. Another twenty minutes passed by into time history before they reached the top of the escarpment and stood looking down its side. The canyon was about seventy-five yards long, perhaps thirty-five feet deep, and a hundred feet wide at the top. The two sides were formed of jagged rock with treacherous spots of crumpling sand-stone here and there. There was plenty of brush and shrubbery about, however, and it was thick enough to cast patches of shade regardless of the burning rays of the sun. One point struck them at once as being an ideal spot where they could relax and rest until the sun was deep in the west, and the cooling winds of night were beginning to steal across the desert. It was to their left and about halfway down. A shelf of rock jutted outward a bit. As a matter of fact, it was really two shelves of rock that jutted out. The bottom one served as a platform upon which to rest. And the top shelf, rimmed with thick desert bush, served as a roof, a sort of canopy for the shelf lower down. Fortunately the side of the escarpment was not too steep to make it impossible for them to reach the lower shelf.

"That's us, Freddy!" Dave exclaimed, and pointed to it. "We'll get down there and be cliff dwellers until it's cool enough to start getting underway again. I vote that we get down there pronto, and have a bit to eat and a little water. That's our biggest danger—water. We must save every drop we can. Who knows when—"

Dave stopped short, and a horrified look leaped into his eyes. He pointed his finger at Freddy and worked his mouth, but no words came from his lips. The English youth stared at him and impulsively recoiled a step in surprise and amazement.