Mr. Holmes calls attention to one point bearing on the antiquity of this ruin. The buttresses, which probably support a balustrade, noticed in the figure on the house, were built on the sloping surface of the rock. It would take but very little weathering of the rocks to throw them to the bottom of the cañon; and, furthermore, the rock is a rough sandstone, and hence easily crumbles; and it is not well protected by the overhanging cliff; but no perceptible change has taken place since the buttresses were first built. The thickness of a sheet of paper has hardly been washed from the surface, and the mortar, almost as hard as the rock itself, lies upon it as if placed there within a dozen years. This structure is, evidently, not as old as the low mounds of crumbling ruins we have heretofore described. It is more than probable that such retreats as this were not provided until near the close of their stay in the country. A ruin further down the cañon, described by Mr. Holmes, is of great interest, as it shows how necessary the people considered it to be to construct an estufa. It will be observed that there are two houses. So nicely are these hidden away that Mr. Holmes had almost completed a sketch of the upper house before he noticed the lower one. They are both overhung by the rocks above so as to be protected from the weather. The upper house can only be approached by means of steps cut in the rock. It appears to be in an unfinished state, and, when we consider the great labor required for its construction, we can not wonder that they grew tired before its completion. The lower house is some eight hundred feet above the bottom of the cañon, but is comparatively easy of approach. The interesting feature about it is the estufa. It was situated near the center of the main portion of the house. The entrance to this chamber shows the peculiar importance attached to it by the builders. Mr. Holmes says: “A walled and covered passage-way of solid masonry, ten feet of which is still intact, leads from an outer chamber through the small intervening apartments into the circular one. It is possible that this originally extended to the outer wall, and was entered from the outside. If so, the person desiring to visit the estufa would have to enter the aperture about twenty-two inches high by thirty wide, and crawl, in the the most abject manner possible, through a tube-like passage-way nearly twenty feet in length.”