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Investigating the use of land during the medieval period at the celebrated ceremonial area of Angkor, the authors took a soil column over 2.5m deep from the inner moat of the Bakong temple. The dated pollen sequence showed that the temple moat was dug in the eighth century AD and that the agriculture of the immediate area subsequently flourished. In the tenth century AD agriculture declined and the moat became choked with water-plants. It was at this time, according to historical documents, that a new centre at Phnom Bakeng was founded by Yasovarman I. Keywords: Angkor, Cambodia, Southeast Asia, palynology, Borassus, agriculture, Introduction Angkor was the location of the capital of the Khmer state for most of the period from the eighth to sometime in the fifteenth and sixteenth centuries AD. By [...]

A palynologist describes efforts to determine the historical impact of human beings on the environment in Thailand by studying the pollen counts in earth sediments. Studying samples from 6500 years ago, the author finds a decrease in pollen and an increase in charcoal, suggesting activities of a prehistoric human settlement earlier than previous studies have noted.

Historical societies reshaped their environment in various ways; by clearing forest, cultivating crops, mining, and modifying waterways. Evidence of these activities persists in palaeoenvironmental archives, which represent comprehensive histories of human activity in a landscape. Analysis of settlement networks across landscapes is another common approach to investigating how past societies operated, but these analyses rarely incorporate palaeoenvironmental data. Here, we combine these two data sources to examine past socio‐political relationships in a society that experienced disruption and transformation. Applying network analysis, and using settlement histories built from palaeoenvironmental proxies for occupation and land use, this paper reconstructs population dynamics at several key nodes (cities) within the Khmer kingdom of Southeast Asia, before and after the climate stress and political upheaval of the 14th–15th centuries ce. Our results reveal how the Khmer city network transformed across space and the nature of the relationships that existed within the network prior to its disruption. [ABSTRACT FROM AUTHOR]

The River Murray Estuary, South Australia exhibits a morphology typical of a wave-dominated estuary and comprises two large, shallow central basin lakes – Lakes Alexandrina and Albert. Contested interpretations of the estuary's limnological history and uncertainty surrounding the sustainability of current basin water usage practice warrant a robust investigation into how the system has evolved. Here we combine lithostratigraphic, geochemical and sedimentological evidence from a transect of sediment cores to reconstruct the sediment infill history of the system. We uncover multiple stages of sediment infill over the history of the system, associated with (1) the low gradient morphology of the estuary and lower river channel, (2) the mid- to late-Holocene sea-level regression and (3) anthropogenic modifications to the fluvio-estuarine system. We show that while estuarine conditions in the system were fully established during the mid-Holocene highstand (~6.4 kyr BP), central basin facies sedimentation was focussed further inland before prograding with the lowering of base level and shifting of tidal influence as sea-level fell. Central basin facies sedimentation within northern Lake Albert occurred from 5.4 to 4.0 cal kyr BP at ~0.25 cm yr-1. The uppermost accumulation of this unit was eroded by continued reduction in base level until sea-level regression concluded at 3.5 cal kyr BP. Barrage and weir installation (1940 CE) re-initiated and expanded central basin facies sedimentation in the estuary (~0.32 cm yr-1). Recently deposited sediments exhibit geochemical markers of increased trophy and more frequent acid sulfate soil acidification, exposing human impacts on the estuary. [ABSTRACT FROM AUTHOR]

We report the chronological construction for the top portion of a speleothem, PC1, from southern Cambodia with the aim of reconstructing a continuous high-resolution climate record covering the fluorescence and decline of the medieval Khmer kingdom and its capital at Angkor (~9th-15th centuries AD). Earlier attempts to date PC1 by the standard U-Th method proved unsuccessful. We have therefore dated this speleothem using radiocarbon. Fifty carbonate samples along the growth axis of PC1 were collected for accelerator mass spectrometry (AMS) analysis. Chronological reconstruction for PC1 was achieved using two different approaches described by Hua et al. (2012a) and Lechleitner et al. (2016a). Excellent concordance between the two age-depth models indicates that the top ~47mm of PC1 grew during the last millennium with a growth hiatus during ~1250-1650 AD, resulting from a large change in measured 14C values at 34.4-35.2mm depth. The timing of the growth hiatus covers the period of decades-long droughts during the 14th-16th centuries AD indicated in regional climate records. [ABSTRACT FROM AUTHOR]