Contents lists available at ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint Geoarchaeology and taphonomy: Deciphering site formation processes for late Holocene archaeological settings in the eastern Pampa-Patagonian transition, Argentina Gustavo A. Martínez a,* , Gustavo Martínez b , Ana Paula Alcaráz b , Luciana Stoessel b a Instituto de Geología de Costas y del Cuaternario – CIC, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata - IIMyC-CONICET, Mar del Plata, Argentina b INCUAPA-CONICET. Instituto de Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano, Facultad de Ciencias Sociales, UNICEN. Olavarría, Buenos Aires, Argentina ARTICLE INFO Keywords: Colorado river Late holocene Hunter-gatherers Geoarchaeology Taphonomy Site formation processes ABSTRACT Assessing the integrity and resolution of archaeological sites in sandy environments is a key issue for under- standing site formation processes in hunter-gatherer's contexts. A case study from the lower course of the Colorado River, at the eastern Pampa-Patagonian transition (Argentina) is presented here. The studied area is characterized by a sand dune relief that is superimposed upon ancient fluvial and marine environments. The sites date to between c. 2000 and 250 14 C yr BP (late Holocene) and they are mostly located in eolian contexts. The objective of this paper is to understand environmental dynamics and the site formation processes that operated in archaeological sites of the late Holocene through the integration of geoarchaeological and taphonomic in- formation. The obtained results allowed the identification of site formation processes related to the different environmental settings (coast, ancient delta and inland). However, general patterns that relate some taphonomic effects as root action and weathering with landscape processes such as pedogenesis at an areal scale were also recognized. Despite the varied and highly dynamic environmental conditions of this arid-semiarid area, ar- chaeological contexts with good degrees of resolution and integrity were recognized. 1. Introduction The analysis of sedimentary environments is a key aspect in the study of site formation processes at archaeological sites. Deposition and erosion rates as well as periods of stability of the landscape represented by pedogenesis strongly influence both the preservation and the spatial relationship among archaeological remains (Ferring, 1992; Ward and Larcombe, 2003). Soil development is associated with particular con- ditions regarding the preservation of archaeological materials. A buried soil at an archaeological site is interpreted as a stable landscape with slow sedimentation rates over a relatively long time (Holliday, 1992; Mandel, 1992; Goldberg and Macphail, 2006). The morphogenetic and pedogenetic processes mentioned above in a highly dynamic environ- ment dominated by eolian conditions under arid and semi-arid regimes have an important effect on the structure of the archaeological record (Goldberg and Macphail, 2006). In this sense, due to the dynamic nature of the sand dunes, the original archaeological context of a given site can be severely modified or destroyed as a result of post- occupational geomorphic processes (Leigh, 1998). Consequently, un- derstanding geomorphic and pedological processes is important before interpreting human behavior from archaeological assemblages (Schiffer, 1983; Retallack, 1990; Mayer, 2001). Understanding the role of these processes allows a comprehensive discussion of the resolution and integrity of archaeological sites (Binford, 1992; Ebert, 1992; Stein, 1993; Bailey, 2007). The discussion of these issues has been part of the research agendas concerning the development of archaeology as a discipline in Argentina. The volume of information generated in the field of geoarchaeology has significantly grown during the last 20 years and its application has been fulfilled in different regions of the country (see Zárate, 2016; Favier Dubois et al., 2016; and references therein). Also, research in the field of taphonomy has been systematically applied in Pampa and Patagonia since the 1980's (Borrero, 1988, 2001; Politis and Madrid, 1988; Borella, 2000; Gutiérrez, 2004; Gutiérrez et al., 2007, among many others). Some of this papers deal with site formation processes, integrity and resolution as well as the evaluation of https://doi.org/10.1016/j.quaint.2018.09.020 Received 23 November 2017; Received in revised form 28 June 2018; Accepted 12 September 2018 * Corresponding author. E-mail address: gustavo.gmarti@gmail.com (G.A. Martínez). Quaternary International 511 (2019) 94–106 Available online 15 September 2018 1040-6182/ © 2018 Elsevier Ltd and INQUA. All rights reserved. T