Timber was used as an aid to masonry construction in two ways--as a foundation and as a tie. Many instances can be seen where the walls rest on beams, running, not with them, but across them. These beams were placed directly on the rock, and the front walls rested partly on their ends and partly on the rock itself. Plate LII shows the end of one of these beams. In nine cases out of ten the beams do not appear to have served any useful end, but perhaps if the walls were removed down to the foundations the purpose would be clear. Sometimes a beam was placed on the rock in the line of the wall above it. The single or separate room occupying the western end of the upper cave in the Casa Blanca ruin is an example of this use. The front wall rests on beams, as shown in plate XLVI. Some of the back adobe walls in the eastern part of the upper ruin rest on timbers, and instances of this feature are not uncommon in other parts of the canyon. The southeastern corner of the tower in Mummy Cave ruin in Del Muerto rested on timbers apparently laid over a small cavity or hole in the rock. The timber was not strong enough to support the weight placed upon it, and consequently gave way, letting the corner of the tower fall out. Cross walls were sometimes tied to front or back walls by timbers built into them, but this method, of which fine examples can be seen in the Chaco ruins, was but slightly practiced here. Timber was used also to prevent the slipping of walls on sloping sites, being placed vertically and built into the masonry; but as this use is a constructive expedient it is discussed under that head. STORAGE AND BURIAL CISTS Facilities for the storage of grain and other produce are essential in the pueblo system of horticulture, as in any other. As a result, storage cists are found everywhere. In the modern pueblos the inner dark rooms, which would otherwise be useless, provide the necessary space, but in the settlements in De Chelly, which were very small as a rule, there were few such rooms, and special structures had to be erected. These differed from the dwelling rooms only in size, although as a rule, perhaps, the openings by which they were entered were not so large as those of the dwellings and were sometimes, possibly always, provided with some means by which they could be closed. [Illustration: Plate LX Plastered Wall in Canyon De Chelly]