STRUCTURE OF TOWERS None of the towers examined have evidences of mural pilasters to support a roof or recesses in the walls as in vaulted-roofed kivas. They are sometimes two stories high, the rafters and flooring resting on ledges of the inner wall. Lateral entrances are common and windows are absent.[42] While the author has found no ruin of the same ground plan as Sun Temple on the Mesa Verde, D-shaped towers or great houses from several localities distantly recall this mysterious building, and there may be an identity in use between Sun Temple and the massive walled structures of the McElmo and Yellow Jacket; what that use was has not thus far been determined.[43] If they were constructed for observatories we can not account for the square tower in the South Fork of Square Tower Canyon, from which one can not even look down the canyon, much less in other directions, hemmed in as it is by cliffs. Isolated towers are often too small for defense; and they show no signs of habitation. [41] Smithson. Misc. Colls., vol. 68, no. 1, 1917. [42] Our knowledge of the entrances into kivas of the vaulted-roofed type is not all that could be desired. Kiva D of Spruce-tree House has a passageway opening through the floor of an adjacent room, and Kiva A of Cliff Palace has the same feature. Doctor Prudden has found lateral entrances from kivas into adjoining rooms in his unit type pueblo. The majority of cliff-dwellers’ kivas show no evidence of lateral entrances. [43] Mr. Jackson, op. cit., p. 415, regarded it likely that the towers were “lookouts or places of refuge for the sheep herders who brought their sheep or goats up here to graze, just as the Navajos used to and as the Utes do at the present time.” This explanation is impossible, for there is no evidence that the builders of the towers had either sheep or goats, the Navajos and the Utes obtaining both from the Spaniards. Are they granaries for storage of corn or places for rites and ceremonies? Do they combine several functions—observation, defense, and storage of food? Thus far in studies of more than 30 towers and great houses not one has been found so well preserved that enough remains to determine its use, and yet their walls are among the best in all southwestern ruins. Some future archeologist may find objects in towers that will demonstrate their function, but from our present knowledge no theory of their use yet suggested is satisfactory.