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Show 10 round towers are very numerous in the valley of the Mancos. From this point alone at least three others are in view, some on the higher promontories, others quite low, within twenty or thirty feet of the riverbed. I visited and measured seven along the lower fifteen miles of the course of this stream. In dimensions they range from ten to sixteen feet in diameter and from five to fifteen feet in height, while the walls are from one to two feet in thickness. They are in nearly every case connected with other structures, mostly rectangular in form. At the mouth of the Maribos, however, a double circle occurs, the smaller one having been the tower proper. It is fifteen feet in diameter, and from eight to ten in height. The larger circular wall is forty feet in diameter and from two to four feet high, and is built tangent to the smaller. This ruin is at the point where the Mancos reaches the alluvial bottom bordering the Bio San Juan, and about one mile above its junction with that river. On the opposite or south side of the river are traces of somewhat extensive ruins, but so indistinct that the character of the original structures cannot be made out, and indeed no single mile of the lower fifty of the Mancos is without such remaius. CAffON OF THE RIO MANCOS. Fifteen miles from its junction with the San Juan, this stream emerges from the southwest border of the Mesa Verde, through which it has cut its way, producing a most remarkable caDon. This canon has already been once or twice described: but, in order to make my subsequent descriptions better understood, I shall give here an outline. The Mesa Verde is a somewhat irregular table- land, comprising an area of about seven hundred square miles, and is formed of a great series of nearly horizontal sedimentary rocks, of which the surrounding country has been denuded This series of strata consists, in the upper part, of massive sandstones; in the middle part, of alternating sandstones and shales; and in the lower one thousand feet, chiefly of shales and clay. These softer beds are, when once exposed to the erosive agents, carried away with great rapidity, and, as a consequence, the firmer rocks above are undermined and break down in vertical cliffs, and, where soft and hard beds alternate, a series of steps, with intervening slopes, is formed. It will readily be seen that a cation thus formed would consist in general of a narrow, irregular river- bottom, long steep slopes of debris rising like the arms of a letter V from this, then a succession of steeps and slopes, culminating above in a series of lofty, em battled cliffs. The canon is nearly thirty miles in leugth, and ranges from one to two thousand feet in depth. It seems to have been a favorite resort of the cliff- building people, and traces of their industry may be found everywhere, along the bottoms, in the cliffs, and on the high, dry table- lands above. The four following plates will be taken up in the delineation of the more interesting portions of these remains. PLATE IV. Figure 1 illustrates the method of walling up the cave- fronts as described on a preceding page. This sketch was made at the last-mentioned locality on the Rio Mancos. The group occurred in the cliff about thirty feet from the base. The three doorways opened into as many small apartments, and these were connected with each other by very small passage- ways. The farther door could not be reached from the outside, as the platform of rock had broken away. |