Temporal Inflection Points in Decorated Pottery: A Bayesian Refinement of the Late Formative Chronology in the Southern Lake Titicaca Basin, Bolivia

Abstract

The Late Formative period immediately precedes the emergence of Tiwanaku, one of the earliest South American states, yet it is one of the most poorly understood periods in the southern Lake Titicaca Basin (Bolivia). In this article, we refine the ceramic chronology of this period with large sets of dates from eight sites, focusing on temporal inflection points in decorated ceramic styles. These points, estimated here by Bayesian models, index specific moments of change: (1) cal AD 120 (60–170, 95% probability): the first deposition of Kalasasaya red-rimmed and zonally incised styles; (2) cal AD 240 (190–340, 95% probability): a tentative estimate of the final deposition of Kalasasaya zonally incised vessels; (3) cal AD 420 (380–470, 95% probability): the final deposition of Kalasasaya red-rimmed vessels; and (4) cal AD 590 (500–660, 95% probability): the first deposition of Tiwanaku Redwares. These four modeled boundaries anchor an updated Late Formative chronology, which includes the Initial Late Formative phase, a newly identified decorative hiatus between the Middle and Late Formative periods. The models place Qeya and transitional vessels between inflection points 3 and 4 based on regionally consistent stratigraphic sequences. This more precise chronology will enable researchers to explore the trajectories of other contemporary shifts during this crucial period in Lake Titicaca Basin's prehistory.

Radiocarbon vs. Luminescence Dating of Archaeological Ceramics in the Southern Andes: A Review of Paired Dates, Bayesian Models, and a Pilot Study

“…Carbon and artifact concentrations were dense within the house. A 14 C date from the floor returned a median of AD 1000 (LP-1637; Cambria 2010; Marsh et al 2014), which is consistent with expectations for the associated Agrelo pottery. An undecorated sherd from a different part of the house was submitted for luminescence dating (UW-3757).…”

“…It is not impossible that Inca-style ceramics were produced after the fall of the Inca empire, but such late dates have not been documented anywhere else and are likely underestimates. The dates are notably later than 14 C-based estimates that the Inca empire was in the area roughly AD 1400-1550 (Greco 2012;Marsh et al 2017).…”

“…Barrancas, B61. In the southern Andes, ceramics were first adopted in multiple regions around ~150 cal BC (Marsh 2017). This includes Barrancas, a lowland area with the region's earliest cemetery (Novellino et al 2013) and pit house at the site B61, which has two very similar 14 C dates (LP-2997 and LP-3088; Marsh 2017).…”

“…At the lakeshore site Huajje, TL dates were corrected for feldspar fading and mostly matched temporal expectations (Schultze 2008: 391-397). In the southern Lake Titicaca Basin, TL dates from Qeya-style museum pieces in France underestimate the style's expected date range, based on Bayesian models of 14 C dates and stratigraphy (Marsh et al 2019;A. Roddick, personal communication 2021).…”

“…Recent improvements in radiocarbon ( 14 C) dating methods and Bayesian models have led to significant refinements to the cultural chronologies of many regions of South America, even the short-lived Inca empire (e.g., Rick et al 2009;Marsh 2012;Koons and Alex 2014;Korpisaari et al 2014;Marsh et al 2017Marsh et al , 2019. Improving chronologies has required researchers to identify problematic dates that suffer from issues such as old wood, inadequate pretreatment, and unclear artifact associations.…”