VOL. 18, 1932 ANTHROPOLOGY: G. C. VAILLANT 487 STRATIGRAPHICAL RESEARCH IN CENTRAL By GEORGE C. VAILLANT DEPARTmENT OF ANTHROPOLOGY, AMERICAN MUSEUM OF NATURAL HISTORY Communicated June 15, 1932 The establishment of culture sequence is one of the fundamental aspects of archaeology. Beginning with the earliest discovered cultures in the Valley of Mexico, the American Museum of Natural History has devoted five digging seasons to that end, under the direction of the writer, assisted by his wife, and under the inspection of the Department of Historic Monuments of the Ministry of Public Education of the Mexican Govern- ment. During the winter of 1931-32, the focal point of our study was the relationship of the culture of San Juan Teotihuacan, sometimes known as Toltec, and the so-called "archaic" cultures of Zacatencol and Ticoman.2 The work fell into four phases: 1. Analysis of depositions at Group 5' west of the Pyramid of the Moon at San Juan Teotihuacan. 2. Analysis of an early site at Gualupita, Cuernavaca, Morelos. 3.. Study of a culture found at San Francisco Mazapan adjacent to Teotihuacan. 4. The sinking of pits at various points around San Juan Teotihuacan and the running of shafts into the Pyramids of the Sun and Moon. Although the final results are not yet fully digested and correlated, certain salient points appear. At Group 5' at Teotihuacan a careful study was made of the terrain to ascertain whether or not heaps of rubbish existed which were susceptible of stratigraphical dissection. It was found that such heaps did not exist in the vicinity of monuments, and whatever accumulations that may have been formed were utilized to provide adobe bricks for buildings or as foundation material for floors. However, three ceramic periods seemed to be discernible. An early phase (characterized by the predominance of painted over incised decoration) was found in the adobes of the main precinct wall of the group. A middle phase occurred in the foundations for floors outside of and doubtless later than the original precinct. This pottery showed a strong emphasis on incised decoration, and black ware was extensively utilized. The third and latest phase was found above all floors. Gray wares tended to replace the black, and the so-called portrait type of figurine was common. The Gualupita work, the second phase of our investigation, yielded excellent results, three periods being found. First an early period showing Downloaded by guest on September 25, 2021 488 ANTHROPOLOGY: G. C. VAILLANT PROC. N. A-. S. figurine heads associable although not identical with early periods at Zacatenco and El Arbolillo. This material was contained in a sort of platform or revetment against which had accumulated debris of a later period, containing sherds similar to those found in Ticoman. Yet one or two sherds occurred that seem to have emanated from Teotihuacan. Resting above these deposits was a layer of pottery which contained a polished red and a polychrome ware distinctive of Aztec times, but which lacked the characteristic black on orange of the Valley of Mexico Aztec. In the bottom strata of Gualupita a number of burials were found, the bones of which had almost disintegrated, but which had pots and figurines as funeral furniture. Moreover, in the 150 burials of the early cultures opened by us in the Valley of Mexico, figurines were never buried with the dead. At Gualupita, then, there were three periods, an early one connecting with Early and Middle Zacatenco, a middle which had cul- tural connections with Ticoman but was chronologically tied in with Teotihuacan and a late period which, although closely affiliated with Aztec, lacked the characteristic culture diagnostic of black on orange pottery. The third phase of the digging brought us back to San Juan Teotihuacan. A farmer living in San Francisco Mazapan had discovered on his property a burial richly equipped with pottery vessels. Further exploration by us revealed a series of nine skulls, each in a bowl with another inverted over it, but the body bones of only one individual were found. Some eighteen caches of pots were also uncovered and finally two burials with a lavish offering of pottery vessels were exhumed. Two of these bowls were very finely executed portrait vases. This ceramic upon analysis was not "archaic," nor was it Teotihuacan or Aztec. But, as Aztec sherds were found in the top soil, and as Mazapan debris was found over- lying Teotihuacan material at the pyramid site, this Mazapan culture may be assigned with some confidence to a post-Teotihuacan, but pre- Aztec date. The material is significant as filling in that gap in the history of the Valley sometimes referred to as the Chichimec period. The fourth phase of our digging, comprising the sinking of pits at San Juan Teotihuacan, tended to confirm our suspicions as to the sequence of types. The ceramic material found in the pyramids of the Sun and Moon showed a predominance of painted pottery over incised. This pottery was by no means identical with or derived from the early culture sites of Zacatenco, Ticoman and El Arbolillo, although it might be called "Archaic Teotihuacan." In fact, indications at Gualupita and at Tico- man as well, strongly suggest partial contemporaneity between Teoti- huacan and the latter phases of the Early Cultures. Other pits confirmed our estimate that the black and carved wares gave way to rising propor- tions of gray ware in the upper cuts. Downloaded by guest on September 25, 2021 VOL. 18, 1932 ANTHROPOLOGY: G. C. VAILLANT 489 In the town of San Sebastian a pit was dug in five equal layers. The bottom and fifth stratum showed a mixture of Mazapan and late Teoti- huacan sherds. The next two layers produced Mazapan sherds with the addition of Aztec polished red, but the two top layers revealed this polished red associated with the regulation Aztec black on orange. Thus the resemblance of the third and fourth cuts of San Sebastian to the top layer of Gualupita in that black and orange is absent while the polished red wares are most common, may mean that the former ware is associable with the Tenochtitlan Aztecs and may therefore serve as a diagnostic in tracing their domination over the other Nahua tribes in the Valley. The salient results of the season may be said to consist of finding local

CERAMIC SEQUENCE IN THE VALLEY OF MEXICO

Tenochtitlan (A) (A)I Texcoco (A) Teopanzalco (A) Middle (?) Tenayuca (A) Acolhua? (A) Gualupita III (A)

San Juanico III (M) Mazapan (M) El Arbolillo IIl (M-T) Coyotlatelco (T)

Late Teotihuacan (T) Sub-Tenayuca (E?) Late Ticoman (E) Middle Teotihuacan (T) (E) Middle Ticoman (E) Gualupita II (E) Early Ticoman- Early Teotihuacan (T) Late Zacatenco (E)

San Juanico II (E) Middle Zacatenco- Copilco (E) El Arbolillo 11 (E)

San Juanico I (E) Early Zacatenco- Gualupita I (E) El Arbolillo I (E)

Undiscovered stages culturally equivalent to Basket Maker I-Pueblob IV

variations of the Early Cultures at Cuernavaca, establishing the fact that the Teotihuacan culture was not derived from Valley groups of the Early periods, arranging a ceramic sequence of three periods for Teoti- huacan and thereby dating as posterior the site of Coyotlatelco near , defining the Mazapan culture and dating it as post-Teoti- huacan and pre-Aztec, and lastly, finding a suggestive means of dis- tinguishing Tenochtitlan Aztec remains from those of their predecessors like the Acolhuas, the Tlahuicas, the Tepanecas, etc. The ceramic sequence of the Valley of Mexico is expressed herewith in tabular form. Although further research will expand and change many of the details, the salient points will probably stand the rigid criticism of future study. The data will be published in full in the Anthropological Downloaded by guest on September 25, 2021 490 CHEMISTR Y: DA VIDSON AND BOGERT PROC. N. A. S. Papers of the American Museum of Natural History. The qualitative grouping of the sites is expressed by letters, A-Aztec, M-Mazapan, T-Teotihuacan, E-early or "archaic" cultures. 1 Vaillant, George C., "Excavations at Zacatenco," Anthropological Papers of the American Museum of Natural History, 32, part 1, New York (1930). 2 Vaillant, George C., "Excavations at Ticoman," Anthropological Papers of the American Museum of Natural History, 32, part 2, New York (1931). 3 A comprehensive study of this site is about to be published by the Department of Historic Monuments of the Mexican Government. It will give a fuller periodization than the above.

ISO VIOL URIC ACID (ALLOXAN-6-OXIME) * By DAVID DAVIDSON AND MARSTON T. BOGERT CHEMICAL LABORATORY, COLUMBI UNIVERSITY Communicated May 23, 1932 Introduction Since its discovery by Baeyerl violuric acid (II) has been of perennial interest to chemists, largely on account of the beautifully colored salts which it forms. Baeyer prepared this substance by the action of nitrous acid on barbituric acid (I), while Ceresole2 showed that it could be pro- duced by the action of hydroxylamine hydrochloride on alloxan (III). NH-CO NH-CO NH-CO HNO2 | NH20H CO CH2 - >-* CO C:NOH < CO CO HCI .NH-CO NH-CO NH-CO I II III We have found that the action of nitrous acid on isobarbituric acid (IV) leads to the formation of an isomer of violuric acid which we term iso- violuric acid (VI). Since the phenolic character of isobarbituric acid has been established by its behavior toward acetic anhydride, hydroxyl- amine, hypobromous acid,8 diazomethane4 and potassium ferricyanide,5 it was anticipated that 5-hydroxy-6-nitrosouracil (V) would be obtained. The behavior of the product, however, indicated it to be the tautomeric form (VI) (alloxan-6-oxime). * Contribution from the Chemical Laboratories of Columbia University, with the cooperation of the Research Department of the American Manufacturers of Toilet Articles. The authors gratefully acknowledge financial aid received from the Warren fund of the American Academy of Arts and Sciences. Downloaded by guest on September 25, 2021