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Paleoenvironmental studies are critical not only for climatic and environmental reconstructions but also for assessing some of the biggest social transformations. In Peruvian Prehistory, some of the major cultural changes in this part of the world occurred during the Early Intermediate Period (c.200-700 A.D.). The urbanization process started during this time, as well as the emergence of the first archaic states, and some of the most complex pre Columbian societies (such as Moche, Lima, and Nasca) rose and collapsed during this period. Throughout this time, severe natural phenomena could have played a key role in these changes.
The Lima was a pre-Columbian society that flourished in the Central Coast of Peru in the period between ca. 250-750 A.D. Its territory comprised four current valleys: Chancay, Chillón, Rímac, and Lurín. The Maranga Complex was the core of the Lima society in the Rimac Valley, Central Coast of Peru approximately in the period between 500-750 A.D. The Huaca 20 site was a domestic unit, part of the Maranga Complex, whose inhabitants were mainly dedicated to the processing and extraction of marine species. Toward the end of the Early Intermediate period (~600-750 AD), after the site was partially destroyed by heavy rainfall and covered by alluvial deposits, Huaca 20 was no longer a domestic space and instead became a big cemetery. This fact coincides with three major changes that appear to have happened roughly at the same time in the Rimac Valley:
- The political decay of the Lima society, likely associated with the abandonment (partial or total) of sites in the lower valley).
- The relevance gained by highland groups, visible through the influences of ceramic styles, funerary patterns, and highland products.
- Climatic disruptions such as strong precipitations and severe droughts.
My investigation at Huaca 20 analyzes these transformations from the perspective of a household space related to an elite settlement (the Maranga Complex). I will also use the geomorphologic characterization of the Rimac Valley to assess the possible effects that events such as strong or mega El Niño can have in this valley, and the role that human alteration of the natural landscape played in these catastrophic episodes.
The 2010 expedition was focused on the analysis of archaeological findings that were encountered during my previous excavation seasons in Peru.
The malacological analysis revealed that 13 species were consumed and processed by the Huaca 20 inhabitants. This analysis showed that the people of Huaca 20 were exploiting mostly rocky beaches during the first moments of occupations of this site; toward later times species from sandy beaches became more popular than previously. This fact seems to coincide with El Niño-driven sediments that are deposited along the shoreline after this kind of phenomenon. This event could have caused patches of fine sediment accumulation along the Lima littoral that Huaca 20 inhabitants took advantage of. This evidence seems to be contemporary with the pluvial moment in the Quelccaya ice core records.
Twenty two fish species have been recognized. Among the botanical species, maize, cotton, a variety of bean (indigenous from the upper-valley regions), and quinoa were the most frequent remains, these species were found in garbage holes and inside funerary vessels. This fact shows the interaction among coastal groups and middle and upper valley populations, this interaction has been documented in the Huancayo Alto site, in the Chillón Valley (north of Rímac Valley),by Dillehay in 1979.
The lithic analysis identified a good assemblage of fishing-related tools (such as cast net weights, trawl line/hand line weights, gill net weights, mesh tools, knifes, scaling and cleaning stone tools), and some pottery-related artifacts (stone polishers).
The ceramic analysis helped me to identify the two main occupation phases of Huaca 20, the Middle Lima phase (between ca. AD 500 to 600) and the Late Lima phase (between ca. AD 600 to 750). The Middle phase of this site reveals an early occupancy of the Lima in this valley and constitutes an important data for the analysis of the expansion of the Lima in the Central Coast.
Almost 300 burials were encountered in cemetery phase in Huaca 20. During this moment, the whole area of Huaca 20 was used to bury people, these tombs had Late Lima ceramics (phases 8 and 9) but there were some new elements that tell about their chronological location and cultural innovations. The classic Lima burial pattern is the ventral extended position for the Early Lima Period and Middle Lima Period, changing to the dorsal extended position in the Late Lima Period (LLP). Even though, during the last stages of the LLP, two other new patterns showed up: the semi-extended and the sited positions. The first one seems to be an archaism from the Early Horizon and the second one is an evidence of the presence of upper valley/highland people in the coast. Along with these innovations in the burial pattern, there were new elements that became part of the grave goods, pieces of a blue stone called dumorterite, little stones sculptures locally called “illas”, obsidian points, and little sculptoric ceramic pieces depicting llamas or camelids that are locally called “conopas”. All of these elements have an upper valley or a highland origin.
In order to obtain information about geography and geomorphology of Lima valleys, as well as historical accounts, I visited libraries of several institutions such as Instituto Geologico Minero y Metalurgico del Peru, Instituto de Defensa Civil, Sociedad Geologica de Lima, Universidad Nacional de Ingenieria, Universidad Catolica del Peru, Instituto Riva Aguero, and Municipalidad Provincial de Lima. In the Servicio Aerofotografico Nacional, I also acquired aerial photos of the entire Maranga Complex from 1944, which will be used to assess the topography of Lima prior to the urban explosion of the 1950s and 1960s.
During summer 2010 I obtained more information about Huaca 20 which suggests that climatic instability, social decline, and highland group incursions were happening at this time (~600 A.D.). Even tough, this people displayed strategies in order to adapt themselves to these changes and ultimately ensure continuity of their societies. They adapted their economy by adding more products to their diet and adopted prestigious foreign ceramic styles to keep their social status. All of this seems to be an effort to reduce the effects of climatic instability.
The Lima displayed a set of strategies during turmoil and never seems to have been socially incapable of adaptation and transformation. Even tough, at some point their material presence as Lima ceased in the central coast and a new highland-like style became the dominant in this part of the central coast of Peru. So far, the Lima ending tells about a process of decay whose length, sings, and afterwards remains unclear.
I am very grateful for the generous support that the Dan and Betty Churchill Expedition Fund gave to my archaeological research in Peru. Without this help I couldn’t have completed either laboratory analyses or data searching. As this is an archaeological investigation, all analyses must be done in Peru because it is hard to bring materials out of the country and it is more expensive. Besides, most of the geological, geomorphological and historical data are unpublished reports only available in Lima.
I also have to thank the support I received from The Graduate Student Government, the Fulbright Commission Exchange Program, and Pontificia Universidad Catolica del Peru. The support given to this research constitutes a great contribution to Andean archaeological studies.