40 BUREAU OF AMEIUC!AN ETHNOLOGY [bull. 74 



found above the stratum of stone on that side. It is not improbable 

 that at this time the space between Fk)or B and Rooms III and IV 

 and the southern end of Room I was filled in over the floor of the 

 Terrace. In the same way the Northern Terrace was covered by the 

 filling between the high level Floor B' and Rooms V and VI and the 

 northern end of Room I. There is some evidence to show that the 

 high level floor on the east ran to the eastern wall of the Patio, thus 

 covering the Eastern Terrace. All this would greatly enlarge the 

 area of the Main Structure by making these high floors on the four 

 sides a part of the building which had already been increased in 

 area by the additions made in Period IV. 



Period VII. — As has already been noted, it is impossible to differ- 

 entiate with absolute certainty the floors and walls made by the 

 Toltecs from those erected by the Aztecs. The site was probably 

 occupied continuously from one culture to the other. From a study 

 of the distribution of the different types of pottery and figurines it 

 seems probable that the site was occupied by people of the pre- Aztec 

 or Toltec culture up to about the end of Period VI. The changes 

 which are noted in the succeeding periods were made, in all prob- 

 ability, by the Aztec people. Period VII is comparatively unim- 

 portant and is not marked by any sweeping changes in the plan of 

 the site. In this seijuence which has been suggested, I have placed 

 in this period the wall set at an angle over Floor M in the northwest- 

 ern corner of the excavation. This floor was covered with debris 

 when the wall now found over it was built. This wall also extended 

 over Floor B'. It is the only construction in the whole site which 

 does not show a more or less careful orientation. 



The elevated Floor E at the southeastern corner of Room XI has 

 also been placed in this period. There is no proof that the walls 

 over Floor M and Floor E were built at the same time, but they both 

 evidently belong to the Aztec period and, are insignificant changes 

 compared with those which have been placed in Periods VIII and IX. 



Period VIII. — Floor A is important as it is marked by the most 

 sweeping changes in the plan of the Main Structure. This period 

 almost certainly belongs to Aztec times, as much Aztec pottery was 

 found in connecticm Avith this floor. Around the Patio a stone wall 

 was built and the space between filled in to support Floor A. There 

 are some grounds for thinking that Rooms I and III- VI still con- 

 tinued to be used after Floor A Avas built. The straight lines of 

 Floor A on the western and northern- sides make it appear as if 

 these were at one time, at least, the limits of the floor. The stone 

 buttresses of the wall on the western side of A would not have been 

 needed if the floor had extended to the west over Room I. 



Period IX. — This is the last epoch in this suggested sequence in 

 the history of the site. Rooms I and II were filled in together, in all 



