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We discuss how the Chinchorro population of hunter-gatherers and fishermen organized their mobility patterns between the rich marine ecosystems of the Pacific coast and the extreme hyperarid core of the Atacama Desert through the application of strontium isotopes (87Sr/86Sr). We analyzed tooth enamel samples of 35 individuals from the coast (n = 28), inland oasis (n = 6), and the Andean highlands (n = 1). The Sr isotopic composition of modern and archaeological bone samples from sea mammals and land herbivores were obtained from 10 localities. Coastal human individuals show a similar Sr signal to sea mammals, confirming that the former were born and raised in the littoral zone. These results along with archaeological data suggest that the Chinchorro maintained logistic mobility along the coast. Similarly, a woman buried in the highlands (Patapatane) has a Sr signal closer to marine values, suggesting that some Chinchorro also maintained a logistic mobility linked to the Andean interior. In contrast, the Sr ratios of individuals from the inland oasis (Tiliviche) are intermediate between marine Sr values and those of local fauna. This seems to indicate that, although these Chinchorro individuals were raised in this oasis, they were part of a broad logistic mobility pattern connected with the coast.

Archaeological sites composed only of surficial lithics are widespread in arid environments. Numerical dating of such sites is challenging, however, and even establishing a relative chronology can be daunting. One potentially helpful method for assigning relative chronologies is to use lithic weathering, on the assumption that the most weathered artifacts are also the oldest. Yet, few studies have systematically assessed how local environmental processes affect weathering of surficial lithics. Using macroscopic analyses, we compared the weathering of surficial lithic assemblages from seven mid-to-late Holocene archaeological sites sampled from four different microenvironments in the Atacama Desert of northern Chile. Changes in polish, texture, shine, and color were used to establish significant differences in weathering between two kinds of locations: interfluves and canyon sites. Lithics from interfluve sites were moderately to highly weathered by wind and possessed a dark coating, whereas canyon lithics were mildly weathered despite greater exposure to moisture, often lacked indications of eolian abrasion, and lacked dark coatings. Our results show that lithic weathering can be used as a proxy for relative age, but only after considering local environmental factors. The power of such chronologies can be improved by combining archaeological, paleoenvironmental, geomorphological, and taphonomic data.