As a whole the Navaho burial cists are much more difficult of access than the ruins, and some of them appear to be now really inaccessible, a statement which can be made of but few ruins. Some of them appear to have been reached from above. The agility and dexterity of the Navaho in climbing the cliffs is remarkable, and possibly some of the sites now apparently inaccessible are not so considered by them. As before stated, there are a number of Navaho foot trails out of the canyon, where shallow pits or holes have been pecked in the rock as an aid in the more difficult places, and similar aids were often employed to afford access to storage and burial cists. Plate LVI shows a site in the lower part of the canyon where such means have been employed. The pits in the rock are so much worn by atmospheric erosion that the ascent now is very dangerous. The cove or ledge to which they lead is about halfway up the cliff, and on it are a number of cists, one of them still intact, with a doorway. The masonry consists of large slabs of sandstone set on edge, sometimes irregularly one above another, the whole being roughly plastered inside and out. About 200 yards farther up the cove, on the same side, there is a series of foot holes leading to a small cave about halfway up, and thence upward and probably out of the canyon. They are probably of Navaho origin. [Illustration: Fig. 68--Cist composed of upright slabs.] The use of stone on edge is apparently confined to these cists. Figure 68 shows a structure which occurs a little above the ruin marked 37 on the map. The walls consist of thin slabs of stone set upright and roughly plastered where they meet. Instances of the use of stone in this way are not uncommon in the pueblo country, and there are a number of examples in De Chelly. As before stated, the typical Navaho burial cist is of dome shape. The roof or upper portion is supported on sticks so arranged as to leave a small square opening in the top. Apparently at some stage in its existence this hole is closed and sealed, but examples were examined which were very old and one which was but twenty-four hours old, but in neither case was the opening closed. Doubtless the opening has some ceremonial significance; it is not of any actual use, as it is too small to permit the passage of a human body. Plate LXII shows a typical cist in good order and another such broken down. These examples occur at the point marked 6 on the map, in the ruin shown in plate LIII. This site is of comparatively easy access, and there are many others equally easy or even more so, but, on the other hand, there are many Sites which now seem to be wholly inaccessible. DEFENSIVE AND CONSTRUCTIVE EXPEDIENTS