As the width of the valley of Laguna creek from Marsh pass to the point where the stream receives its largest branches on the left bank varies, the amount of arable land is greater in some places than in others. In stretches where the stream almost washes the bases of the ruins there could have been no extensive farming lands. The creek meanders through the soft clay and sand which fill the valley to the depth of many feet, forming treacherous banks that are continually falling and changing the course of the stream, so it is quite possible that the present configuration of the valley is very different from what it was when the cliff-dwellings were inhabited. If the occupants once had farms within its limits all traces of them would have long since been obliterated. Although too much credence should not be given to Navaho traditions, it is not unreasonable to believe that in one particular at least they are correct. These state that, before the introduction of sheep, grass was much higher in the level part of the valley than at present, and formerly game (at least the mountain sheep and the antelope) may have been more abundant. This condition would have exerted a marked influence on the life of the cliff-dwellers. Pictographs show that the ancient people, either here or in their former homes, were familiar with these animals, and various objects of bone and horn are significant in this connection. The Navaho National Monument (see sketch map, pl. 22) contains two kinds of ruins,[52] cliff-dwellings and pueblos. Most of the latter are situated on promontories or on low hills. The structural features of the cliff-dwellings are characteristic, their walls being constructed of stone or adobe built against, rarely free from, vertical faces of the cliff. There are two types of kivas, one circular and subterranean, allied to those of the Mesa Verde, the other rectangular, above ground, entered from the sides. The masonry of these northern ruins is crude, resembling that of modern Walpi. The component stones are neither dressed nor smoothed, but the walls are sometimes plastered. There is a great similarity in architecture. No round towers[53] relieve the monotony or impart picturesqueness to the buildings. The walls of ruined pueblos in this region and the ceramic remains closely resemble those at Black Falls on the Little Colorado. A prominent feature of the walls is a _jacal_ construction in which the mud is plastered on wattling between upright poles. The ends of many of these supports project high above the ground, constituting a characteristic feature of the ruins. This method of wall construction is unknown at Black Falls or at Walpi, but survives in modified form in one or more Oraibi kivas and in one at least of the Mesa Verde ruins.[54] It has been described by Mr. Cosmos Mindeleff as common to several ruins in the Canyon de Chelly.