A little below this site there are some well-executed pictographs, and on some rocks immediately to the right some crude work of the Navaho of the same sort. To the left of the cist a round hole 6 or 8 inches in diameter has been pecked into the almost vertical face of the rock. The purpose of this is not clear. The storage of water was so seldom attempted, or perhaps so seldom necessary, that only one example of a reservoir was found. This has already been described (page 126). If the cliff ruins were defensive structures, a supply of water must have been kept in them, and where this requirement was common, as it would be under the hypothesis, certainly some receptacle other than jars of pottery would be provided. Few, if any, of the cliff outlooks are so situated that a supply of water could be procured without descending to the stream bed, and without a supply of water the most impregnable site in the canyon would have little value. The number of burial cists in the canyon is remarkable; there are hundreds of them. Practically every ruin whose walls are still standing contains one or more, some have eight or ten. They are all of Navaho origin and in many of them the remains of Navaho dead may still be seen. Possibly the Navaho taboo of their own dead has brought about the partial taboo of the cliff dwellers' remains which prevails, and which is an element that must be taken into account in any discussion of the antiquity of the ruins. The burial cists are built usually in a corner or against a wall of a cliff dweller's house, but sometimes they are built against a cliff wall, and occasionally stand out alone. The masonry is always rough, much inferior to the old walls against which it generally rests, and usually very flimsy. The structures are dome-shape when standing alone, or in the shape of a section of a dome when placed against other walls. The natural bedding of the stone is sometimes wholly ignored, and in some cases the walls consist merely of thin slabs of stone on edge, held together with masses of mud, the whole presenting an average thickness of less than 3 inches. Such structures on ordinary sites would not last six months; protected as they are they might last for many years. [Illustration: Plate LXI Storage Cist in Canyon De Chelly] Not all the Navaho dead in the canyon find their last resting place in the ruins. Graves can be seen under bowlders and rocks high up on the talus; and in one place in De Chelly a number of little piles of stones are pointed out as the burial places of "many Americans," who, it is said, were killed by the Navaho in their last war. It is also said that in the olden days, when the Navaho considered De Chelly their stronghold and the heart of their country, the remains of prominent men of the tribe were often brought to the canyon for interment in the ruins. Such burials are still made, both in the ruins themselves and in cists on similar sites.