Apparently the greatest care was bestowed on the construction and finish of the kivas. The exterior of the circular wall is often rough and unfinished, but this is probably because the whole structure was generally inclosed within rectangular walls. The interior was plastered, often with a number of coats. The southern kiva in ruin No. 10 shows a number of these on its interior surface, applied one after another, and now forming a plastering nearly three-quarters of an inch thick. In its section 18 distinct coats can be counted, separated one from the other by a thin film of smoke-blackened surface. The kiva in ruin No. 16 has 4 or 5 coats, that in ruin No. 31 shows at least 8. In the last example the last coat was not decorated, but some of the underlying ones were. Kivas are used, principally in the autumn and winter, when the farming season is over and the ceremonies and dances take place. It is probable, therefore, that each coat of plaster means at least a year in the history of the kiva, which would indicate that some of the sites were occupied about twenty years. But Mr Frank H. Cushing has observed in Zuni a ceremony, part of which is the refinishing of the kiva interior, and this occurs only once in four years. This would give a maximum occupancy of about eighty years to some of the kivas; the ruins as a whole would hardly justify an hypothesis of a longer occupancy than this. In Tusayan the interior of the kiva is plastered by the women once every year at the feast of Powamu (the fructifying moon). [Illustration: Fig. 72--Kiva decoration in white.]