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

Erik J Marsh,Scott C Smith,John W Janusek,Christine A Hastorf,Andrew P Roddick,Maria C Bruno

doi:10.1017/laq.2019.73

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.

Highlights

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)
We use a “mixed calibration curve” (Bronk Ramsey and Lee 2013:722) that takes into account the unknown degree of mixture of atmospheric carbon from the Southern and Northern Hemispheres in the southern Lake Titicaca Basin (Marsh et al 2018)
After the end of the Middle Formative around 250 BC, we identify a conspicuous gap with almost no decorated ceramic sherds that we call the Initial Late Formative

Summary

Introduction

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). 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. 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.

Methods

Results

Discussion

Conclusion