A geoarchaeological investigation of the Street of the Dead at the Tlajinga district, Teotihuacan, Mexico.

Archaeological investigations undertaken by the Proyecto Arqueológico Tlajinga Teotihuacán are focused on understanding urban expansion and household economies in this southern district of the city. Our geoarchaeological research addresses similar topics through examination of relevant microstratigraphic and botanical signatures as well as those relevant to reconstructing paleoenvironment. We investigated four different contexts at Tlajinga: the southern extension of the Street of the Dead, an obsidian working area outside Compound 17:S3E1, anthropogenic and natural layers below Compound 18:S3E1, and a soil profile at the San Lorenzo river. We employed micromorphological, pollen, and phytolith analyses as well as standard soil analytics to study the various deposits in these contexts. Our analysis demonstrates artificial lowering of the tepetate for continuing the axis of the Street of the Dead, microdebitage from obsidian working outside Compound 17:S3E1, and the preservation of in situ burning activities at Compound 18:S3E1. Further, we reconstruct alluvial infilling of the Street of the Dead with pedogenetic overprinting and present further evidence on the occurrence and variability of the Black San Pablo Paleosol and its agricultural significance

History of pedogenesis and geomorphic processes in the Valley of Teotihuacán, Mexico:: Micromorphological evidence from a soil catena.

The paper provides new evidence on the pedogeomorphic history of the Valley of Teotihuacán, Mexico. The soil landscape here consists of Luvisol and "black soil", the micromorphology of which allowed us to (a) distinguish between in situ and inherited processes and (b) establish spatial relationships of erosion and sedimentation along a toposequence of three soil profiles. Soil profiles sites were selected by photointerpretation followed by verification on a toposequence from middle mountain slope to colluvial piedmont. Samples of these profiles were characterized by physical and chemical analyses, including micromorphological observation under a petrographic microscope. The results are summarized as geomorphic observations, description and analysis of soil profiles along a catena, and micromorphological features. The final data set permits recognition and interpretation of both present-day pedofeatures and inherited pedofeatures due to past hillslope processes. In the �black soil�, the key processes include development of vertic features, humification and CaCO3 accumulation; while micromorphology revealed fragments of illuvial clay along with disorthic ferruginous nodules. In the Luvisol, clay illuviation dominates and is associated with redoximorphic features. Strongly weathered pumice fragments and less weathered mineral and rock fragments were observed in the vertic horizons. Because the pedofeatures of the �black soil� strongly differ from those of the Luvisol, we can readily identify the cases where Luvisol materials were inherited by the �black soil�. Thus, the micromorphological observations allow us to propose that the �black soil� was likely to incorporate Luvisol materials that were earlier colluviated. The presumed erosional phase may correspond with climatic aridization.Este estudo fornece novas evidências sobre a história pedológica e geomorfológica do Vale de Teotihuacán, México. A paisagem do solo neste local consiste num Luvissolo e num �solo negro�, cujas análises micromorfológicas permitiram: (a) distinguir entre processos in situ e processos herdados, e (b) estabelecer as relações espaciais de erosão/sedimentação através de una catena de três perfis de solo. A selecção dos solos realizou-se com base na fotointerpretação e posterior verificação de uma toposequência que apresentava uma distribuição desde meia encosta até um depósito de sopé coluvial. As amostras destes perfis caracterizaram-se física e quimicamente e por observação micromorfológica de lâminas delgadas com microscópio petrográfico. Os resultados obtidos resumem-se nas observações geomorfológicas, descrição e análise dos perfis do solo da catena Zacatlán, e nos resultados micromorfológicos. O conjunto destes resultados permitiu interpretar e reconhecer quer os processos pedogenéticos actuais quer os herdados devidos ao transporte por erosão do solo em épocas passadas. No �solo negro� os processos chave são o desenvolvimento de propriedades vérticas, a humificação e a acumulação de carbonatos secundários; a micromorfologia também revelou fragmentos de argila iluviada e nódulos ferruginosos disórticos. No Luvissolo domina a iluviação de argila associada a processos redoximórficos. Nos horizontes vérticos observou-se a presença de fragmentos de pedra-pomes fortemente meteorizados coexistindo com fragmentos de rocha e minerais com fraca meteorização. As características pedológicas do �solo negro� diferem fortemente das do Luvissolo, o que permitiu reconhecer características herdadas do Luvissolo nos horizontes do �solo negro�. Assim, as observações micromorfológicas permitem-nos sugerir que o �solo negro� provavelmente incorporou materiais do Luvissolo, anteriormente coluviados. A presumível fase de erosão pode coincidir com uma aridização climática.Este trabajo proporciona nuevas evidencias sobre la historia edafológica y geomorfológica en el Valle de Teotihuacán, México. El paisaje del suelo en este lugar está formado por un Luvisol y un �suelo negro�, cuyos análisis micromorfológicos permitieron: (a) distinguir entre procesos in situ y procesos heredados, y (b) establecer las relaciones espaciales de erosión/sedimentación a través de una catena de tres perfiles de suelo. La selección de los suelos se realizó a partir de fotointerpretación y posterior verificación de una toposecuencia que mostraba una distribución desde ladera media hasta piedemonte coluvial. Las muestras de estos perfiles fueron caracterizadas de manera físico-química, incluyendo la observación micromorfológica de láminas delgadas con microscopio petrográfico. Los resultados obtenidos se resumen en las observaciones geomorfológicas, la descripción y el análisis de los perfiles de suelo de la catena Zacatlán, y los resultados micromorfológicos. El conjunto permitió interpretar y reconocer tanto los procesos edafogenéticos actuales como los heredados debidos al transporte por erosión de suelo en épocas pasadas. En el �suelo negro� los procesos clave son el desarrollo de propiedades vérticas, la humificación y la acumulación de carbonatos secundarios; la micromorfología también reveló fragmentos de arcilla iluviada y nódulos de hierro redepositados. En el Luvisol domina la iluviación de arcilla asociada con procesos redoximórficos. En los horizontes vérticos se observó la presencia de fragmentos de pómez fuertemente meteorizados coexistiendo con fragmentos de roca y minerales con débil meteorización. Los edaforrasgos del �suelo negro� difieren fuertemente de los del Luvisol, lo cual permitió reconocer rasgos heredados del Luvisol en los horizontes del �suelo negro�. Por lo tanto, las observaciones micromorfológicas nos permiten proponer que el �suelo negro� probablemente incorporó materiales del Luvisol, los cuales fueron anteriormente coluviados. La presunta fase de erosión puede corresponder con una aridización climática

STATE AND SOCIETY AT TEOTIHUACAN, MEXICO

Between 100 BCE and 200 CE, the city of Teotihuacan grew rapidly, most of the Basin of Mexico population was relocated in the city, immense civic-religious structures were built, and symbolic and material evidence shows the early importance of war. Rulers were probably able and powerful. Subsequently the city did not grow, and government may have become more collective, with significant constraints on rulers\u27 powers. A state religion centered on war and fertility deities presumably served elite interests, but civic consciousness may also have been encouraged. A female goddess was important but probably not as pervasive as has been suggested. Political control probably did not extend beyond central Mexico, except perhaps for some outposts, and the scale and significance of commerce are unclear. Teotihuacan\u27s prestige, however, spread widely in Mesoamerica, manifested especially in symbols of sacred war, used for their own ends by local elites