526 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 8 



may be divided into six periods, while other local forms and decora- 

 tions reflect the presence of city-states mentioned in the chronicles. 



The six Aztec pottery periods may also be grouped into larger units. 

 The first period has been found in quantity at only one site in the 

 valley, Culhuacan, and stylistically these ceramics show affiliations 

 with Cholula and the Mixteca, and, by trade pieces, with Mazapan. 

 The second and third periods are closely united, and only minor 

 differences in their coarse style of draughtsmanship distinguish them. 

 The fourth and fifth periods produced highly conventionalized designs 

 that are very similar, but many highly decorated polychrome wares 

 attest to a wide trade. The last period styles evolve from the pre- 

 ceding and a new element of naturalistic decoration also appears. 



Here, then, is the logical starting point for a correlation between the 

 archeology of the valley and its documentary history. If the six 

 ceramic periods could be tied in with the annals of the Aztec, then 

 there would be a fairly secure basis for testing the vaguer portions of 

 the valley's past. To this end a curious custom of the Aztec gave us 

 a very good lead. 



The Aztecs at the close of each of their 52-year cycles broke all their 

 household utensils and put out their fires. Then they refurnished 

 their houses and made new equipment. Presumably the temples 

 and sacred buildings underwent a similar renovation. After midnight 

 on the last day, a new fire was kindled on a hill outside of Mexico, and 

 runners with torches distributed this flame to all the hearths in the 

 valley, while every one rejoiced that life was to continue for another 

 52-year span. The native chroniclers record this practice punctili- 

 ously, for the Mexican calendar system was a sacred almanac for 

 governing men's lives and served only secondarily as a means of 

 recording time. 



Reflections of this ceremony have been found in excavations around 

 Mexico City, where broken pottery and idols were found in too great 

 quantity to have been the result of accidents. Ancient temples, in 

 which the successive additions give the nested effect of a Russian doll, 

 also suggest a further application of this practice. 



One of these cyclical dumps yielding pottery of the fifth Aztec style 

 we uncovered in the spring of 1936 at the power plant of Nonoalco in 

 the heart of Mexico City. A normal refuse heap of the sixth and latest 

 style lay above the ceremonial deposit. Since this latest type of Aztec 

 pottery occasionally shows such traces of Spanish influence as glazed 

 surfaces and European designs, it must have been in vogue at the 

 time of the Spanish penetration of Mexico subsequent to 1519. There- 

 fore we had good basis for assuming that the lower layer of the fifth 

 period represented the destruction in connection with the last New 

 Fire Ceremony before the conquest, which was celebrated in 1507. 

 Moreover, at Chiconauhtla, a frontier town of the Texcocan dominion, 



