This ruin is a small tower situated in a commanding position on the point of the mesa where the canyon forks. The section of the wall still standing indicates a circular form, the north side of which has fallen; the part still intact, or that on the south side, exhibits good masonry about 8 feet high (pl. 15, _c_). RUIN 5 The walls of the north segment of a tower stand on a large angular block of stone rising from a ledge above the arroyo, or bed of the canyon, below Ruin 4, on the South Fork. What appears to have been a doorway opens on its north side; this opening is defended by a wall, remains of a former protected passageway into the tower. On the perpendicular cliff of the precipice near Ruin 5 and below the point on which Ruin 4 stands there are several almost illegible pictographs, below which are rather obscure evidences of a building, the features of which can be determined only by excavation. Instructive features of Tower No. 5 are two parallel walls, one on each side of the doorway, like those of the circular towers on the promontory at the junction of the Yellow Jacket and McElmo. Other towers on the canyon rim show defensive walls, as in Ruin 9, constructed about their entrances from corners of the buildings to the mesa rim, effectually preventing passage. Morley and Kidder have suggested that the walled recess in the cliff below Ruin 9 was probably built to prevent access from below. This feature is found in the floor entrances of a building near the Great House of the Holly group. RUIN 6 This ruin is a small tower whose curved walls are so broken down that the form is not evident. It is situated in the base of the talus at the head of the South Fork (pl. 26, _a_). ERODED BOWLDER HOUSE (RUIN 7) This house, more remarkable from its site than its structure, was constructed in an eroded cave of a bowlder halfway down the talus of the cliff. The front walls are somewhat broken down, but others built in the rear of the cave still remain intact. On the top of the bowlder is the débris of fallen walls, suggesting a former tower, but not much remains in place to determine its outlines. Where the walls are protected the mortar shows impressions of human hands and at one place there are the indentations of a corncob used by the plasterers to press the mortar between the layers of stone. There were formerly at least two rooms in the rear of the cave, the front walls of which have fallen and are strewn down the talus to the bottom of the canyon. TWIN TOWERS (RUIN 8)