Date of Award


Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)


Quaternary and Climate Studies


Daniel H. Sandweiss

Second Committee Member

Daniel Belknap

Third Committee Member

Alice Kelly


This M.S. thesis analyzes the human occupation of the Huaca 20 archaeological site, a Late Lima site located in the lower Rimac Valley, Central Coast of Peru. Huaca 20 was a domestic unit of the Maranga Complex (apparently the main settlement of the Late Lima society), between ca. 550 A.D.-700 A.D. Previous excavations carried out at the small mound that originally was Huaca 20, identified occupations associated with the Ichma culture (Late Intermediate Period, ca. 1000-1400 A.D.) (Cardenas 1970a, 1970b; Ramos de Cox 1971:99; Rodriguez and Cordova 1996); Middle Horizon styles such as Nieveria and Chakipampa, and domestic Late Lima evidence associated with several tombs (Mac Kay and Santa Cruz 2002). This study is based on the data produced by new investigations carried out in Huaca 20 between 2005 and 2009. This time the research focused on the Late Lima occupation. Judging from previous dating and ceramic styles, the use of Fluaca 20 can be placed around 550 AD to 750 AD, at the end of the Early Intermediate Period (EIP). The domestic use of Huaca 20 coincided with a time of environmental stress, apparently caused by an unusually strong El Nino event around 600 AD (Shimada et al. 1991). This El Nino event has been cited as a critical factor in the decay of pre-Columbian societies of the EIP such as Moche, Nasca, and Lima. Severe floods and heavy rainfall would have caused serious damage to agricultural fields and rural and urban settlements (Shimada et al 1991, 1994; Dillehay 2001). Consequently, economic and political systems would have been affected by environmental instability. In addition, groups from the highlands would have taken advantage of this moment of instability to take control of coastal territories. New data coming from archaeological excavations in several coastal sites indicate that this El Nino event did, in fact impact these sociedes severely (Kaulicke 1993; Uceda and Canziani 1993; Mogrovejo and Makowski 1999; Segura 2001; Franco 2000; Winsborough et a. 2012). However, the effects of this phenomenon would have been different from valley to valley and the social responses would have been were equally different in each society (Billman and Huckleberry 2008; Goldstein and Magilligan 2011). Within this perspective, this thesis assesses the impact of the ca. 600 A.D. El Nino event by analyzing the development of social dynamics in Huaca 20 before, during, and after this phenomenon. This study is done from the perspective of a domestic fishing unit, a fact that makes it particularly sensitive to trace effects of El Nino on marine environments. My research shows that rainfall and floods severely affected this part of Maranga and the marine resources exploited by the Huaca 20 inhabitants. Nevertheless, the Lima population of Huaca 20 reacted promptly and adapted themselves to cope with this difficult moment. Part of these strategies is reflected in the internal reorganization of the Maranga Complex and in the more visible presence of highland-related styles in the final stage of the Lima occupation at Huaca 20, around 700 A.D.


As of 2002, Degree of Master of Science (MS) Quaternary and Climate Studies published under the auspices of the Climate Change Institute.

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