Shell mounds are an important component of the archaeology of coastal regions in northern Vietnam. Understanding cultural dynamics and settlement patterns within seemingly homogenous layers of shell accumulation is difficult based on field survey and excavation records alone. Here, we use microstratigraphic and microfacies analysis to decipher the complex stratigraphy and thereby reconstruct the occupation history of Thach Lac, a mid Holocene (c. 5000–4100 cal BP) coastal shell-bearing site in Ha Tinh Province, northern-central Vietnam. Our microstratigraphic approach utilises micromorphology, the microscopic study of undisturbed stratigraphic blocks, aided by compositional analyses including Fourier Transform Infrared (FTIR) spectroscopy, particle size analysis and phytolith concentrations. Our results establish that Thach Lac was occupied by three distinct cultures, known as the Quynh Van, Thach Lac and Bau Tro, across a millennium of significant sea level fluctuations in the mid Holocene. During the Quynh Van (5000–4850 cal BP) and Thach Lac (4850–4600 cal BP) occupations, repeated transient shell foraging activities took place across the period of maximum Holocene transgression. As sea levels stabilised to present levels, the site was removed from coastal sedimentary processes and a major subsistence and settlement shift was detected in the later Thach Lac and ensuing Bau Tro (4450–4100 cal BP) phases, based on the change from shell to animal bone deposition and evidence for extended, semi-sedentary occupation. A microstratigraphic approach to shell mound formation at Thach Lac enables high-resolution integration of cultural and environmental sedimentary records, thus affording exceptional insights into prehistoric settlement adaptations and resilience to dynamic coastal environments.
Bibliographical noteFunding Information:
This research formed part of EG's doctoral research completed at the Australian National University funded by an Australian Government Research Training Program Scholarship (2015–2018). EG's laboratory stay at the Charles McBurney Laboratory for Geoarchaeology, University of Cambridge in 2017 was funded by the Australian National University Vice-Chancellor's Travel Grant. Sediments and stratigraphy investigated in this research were sampled from the 2015 excavation of Thach Lac which was funded with support from the Australian Research Council Discovery Grant DP140100384 .
The archaeological excavations and post-excavation analyses at Thach Lac were a collaborative research project between the University of Social Sciences and Humanities, Vietnam National University (Hanoi), the Institute of Archaeology (Hanoi), the Ha Tinh Provincial Museum (Ha Tinh), and the School of Archaeology and Anthropology, Australian National University (Canberra), co-directed by Lam Thi My Dzung, Philip Piper and Peter Bellwood. Thanks are extended to the excavation team: Nguyen Chieu, Nguyen Huy Nham (VNU USSH, Hanoi); Nguyen Thuong Huyen, Tran Phi Cong (Ha Tinh Provincial Museum, Ha Tinh); Tran Thi Kim Quy (ROCEEH, Heidelberg Academy of Sciences and Humanities, Heidelberg, Germany); and, Jasminda Ceron (Department of Anthropology, University of Otago, New Zealand). We acknowledge Adelaide Petrographics for assistance with thin section preparation; Ulrike Proske, Janelle Stevenson and Jack Fenner for laboratory access and support; Andrew Higgins for assistance with Particle Size Analysis; the Kimmel Center for Archaeological Science, Weizmann Institute of Science for the online Library of Infrared Standards which assisted with FTIR spectral identifications; and, the Geoarchaeology Research Group, Australian National University. We thank two reviewers for their careful reading of this manuscript and for providing constructive comments which helped to improve the manuscript. EG would like to thank three anonymous thesis reviewers whose comments improved research presented here. This research formed part of EG's doctoral research completed at the Australian National University funded by an Australian Government Research Training Program Scholarship (2015–2018). EG's laboratory stay at the Charles McBurney Laboratory for Geoarchaeology, University of Cambridge in 2017 was funded by the Australian National University Vice-Chancellor's Travel Grant. Sediments and stratigraphy investigated in this research were sampled from the 2015 excavation of Thach Lac which was funded with support from the Australian Research Council Discovery Grant DP140100384. None.
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- Coastal adaptation
- Sea level change
- Settlement patterns
- Shell middens
- Southeast Asia
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