The rock had a top area of perhaps forty or fifty acres. It had a rolling surface and was coated with a carpet of dusty sand, except in the northwest corner. The northern end of the mesa, Ned could see, widened and ended in a sharp rise almost wall-like in form. At the western end this wall-like elevation turned the corner and extended south a short distance, finally dropping down to the general level of the mesa. In this protected comer grew a strange grove of gnarled and twisted pines, ill nourished and apparently very old. Between this comer of the mesa and the sharper promontory whereon the Cibola had come to anchor, was a wide, sandy, barren depression.

The narrow portion of the rocky island where the boys had made camp drew in abruptly to make the point that marked the southern end of the mesa. Ned turned first toward the point.

When he had advanced, making his way slightly upward all the time, to where the narrow mesa was not over four hundred feet wide, the lad was astounded to suddenly discover a deep and narrow fissure or chasm. It was dark, with sides as abrupt as the cliffs of the mesa, and too wide to jump across. A cold air was already rising from the opening into the warmer atmosphere above.

In his astonishment Ned called to his chum.

"What surprises me," exclaimed Ned, "is the character of the opening. If it extended from cliff to cliff I should say that the same freak of nature that made this solitary island of rock also split off this end at some time. But it is closed at each end."

Alan hastened to the end of the fissure, near the side of the mesa.

"It looks to me," he said, "as if it had extended entirely across at some time and the ends walled up later."

The boys made a closer examination.

"You're right," said Ned when he discovered that each end of the rift had been filled with closely fitted rock, "and human hands did it."

Alan sprang up in excitement.

"That's the first sign we've had," he exclaimed. "Do you suppose it means anything?"

The edge of the cliff was so abrupt that the boys had to lie down to look over in safety.

"It does," Ned answered. "The reason you can't see that chasm from below or from in front is because the face of it is walled up. And it is walled so skillfully that you can't detect it from even a short distance."

"That's to hide something," quickly replied Alan, "but I don't see-- "

Ned was standing on top of the short filled-in portion of the chasm.

"Look!" he exclaimed, suddenly interrupting his friend. "These stones are steps, and, they are worn!"

CHAPTER XXVII

THE TURQUOISE TEMPLE DISCOVERED

In another moment he had sprung forward and was quickly descending into the narrow, dark pit, with Alan close behind. A cave-like smell and a rapidly, cooling air greeted them. They were soon in almost complete darkness. When the walls had narrowed to but a few feet, a thin ribbon of blue sky was all that could be seen above.

The steps had come to an end. An ascending elevation began just in front of them. This they made out by the light of a match, which flickered uncertainly in the bad air. Bats dashed against the walls and every movement was followed by a cloud of dust.

"Do you feel anything?" suddenly exclaimed Alan. "Seems to me like a current of air on my feet."

Ned lit another match.

Before them they again made out an ascending slant such as they had come down. But the base of it was hollowed out in the form of a small cave. As the light went out both boys stooped to look further into this opening.

"Light!" they exclaimed almost together.

They were looking through a tunnel made, as they afterward found, in the base of the filled-in portion of the chasm. Reptiles, bats and dust were forgotten now. Plunging forward on their hands and knees, the two boys advanced without difficulty to the distant mouth of the tunnel.

It ended abruptly in the face of the mesa cliff, one hundred feet above the valley below. There was not the slightest ledge below it and the side of the mesa dropped so precipitately that access to the tunnel mouth from without seemed impossible. The possibility of a climb to that entrance to reach the mesa above was out of the question.

The boys, panting for breath, lay on the floor of the tunnel with their heads just out of the opening.

"Some one has used this place, but how did they ever get up here?"

asked Alan.

"I don't know and I don't care," said Ned with excitement. "But I do know that this entrance is concealed. Why, you couldn't even see it from below--it's so small. And it was made that way for a purpose. That must mean Cibola. Let's get busy."

There were one hundred and thirty-five steps to mount, and each was about a foot and a half high. When Ned and Alan were on top of the mesa again they were out of breath and their clothes were white with dust. They were also choked, thirsty and hungry.

"Eat heartily," laughed Ned, when they began breakfast over again; "we are going to have a busy day, I hope."

"What is your theory?"

"That our treasure is right here if it is anywhere," exclaimed Ned.

Alan laughed. "The place is barren as a barn floor," he said; "I don't see any very large palace or temple hereabouts."

"I don't either. That's why I'm going to look for it--and look hard."

"And our gas slipping away at a lively rate!" interrupted Alan again.

"Let it all go," said Ned. "We know how we can get down within a hundred feet of the ground, anyway. That's some consolation."'

"First we will make a circuit of the north end," continued Ned, after breakfast, "and if nothing comes of that--no unseen hollows or new crevices--we'll try this sandy hollow, even if it is smooth as a plain."

The circuit of a fifty-acre area requires time and it was an hour before the boys had traversed the edge of the precipitous cliff. At every few yards they examined the face of the mesa for gaps or shelves, but there seemed hardly a resting place for a bird.

Tired and hot, the sun being now high above them, the young aeronauts finally reached the north-eastern corner of the mesa without finding a sign or suggestion of Indians, or even of animal remains.

Alan had thrown himself on the ground at this point for a rest, when with an exclamation Ned darted from his side. As Alan's eyes followed him he saw the cause of the exclamation. From where they stood--directly east from the ancient grove--they could see for the first time that the trees stood in a wide double semi-circle, and, directly in the center, perhaps fifteen feet in height, arose a column of masonry. It was snow white in color and glistened like gla.s.s.

There was no question about it.

The fabled Temple of Turquoise, its deep blue glaze lost in the whitening sun of three centuries, stood before them. Almost overcome with the emotion of success the two boys stood as if transfixed. Then cautiously, as if afraid the wonderful pile might dissolve itself into a dream, they moved forward.

In this protected corner of the mesa where the winds of ages had gradually deposited a thin sandy soil, the hand of man had planted two almost complete circles of trees. Therein, and generally agreeing with the record of the long dead Vasquez, were the plain outlines of a stone structure. At places, where the walls crossed, and at some of the corners, the masonry yet rose to the height of a man. And again, it fell into long irregular piles of jumbled blocks. Sifted sand filled each corner and crevice.

In the center of the ruins rose the turquoise column. From this, and in a line with the true east to where the boys stood, extended an open approach. Almost reverently Ned and Alan advanced up this walk.

It was easily seen that the structure had contained a maze of rooms--over three hundred, they afterwards discovered--and that the white column stood in a hollow square.

"It's white," almost whispered Alan.

"Yes," answered Ned; "it ought to be blue."