CRACKING THE CODE OF BUDDHIST COSMOLOGY THROUGH THE ANALYSIS OF HOLOCENE PALEOENVIRONMENTAL ARCHIVES: A PRELIMINARY RECONSTRUCTION OF PALEOLAKE BOROBUDUR (JAVA, INDONESIA)

The 9th century world-heritage Buddhist monument of Borobudur (Java, Indonesia) stands above the floor of a dried-out paleolake, but it remains uncertain as to whether it was ever constructed on a lake shore. Here we reveal through new chronological, geomorphological and paleoenvironmental data on the extant sediment record of the area that Borobudur intentionally stood by an existing natural lake with a life history spanning at least 20,000 years.

Our study combines surface and subsurface data to generate time-sliced maps of paleolake Borobudur. Ground-checked aerial photographs were used to map the surface geology and drainage. The stratigraphy and contours of the paleolake were plotted and correlated after completion of an electrical resistivity and Very Low Frequency electromagnetic survey. Textural, mineralogical and pollen analyses were performed on lacustrine claystone roof exposures and two 50 m-deep cores in order to establish environmental fluctuations, sediment provenances and flooding events. Radiocarbon ages have allowed to age-bracket some of these events and set the claystone stratigraphy, and therefore the history of Borobudur, in a new chronological time frame.

The configuration of the fluctuating lake was intermittently influenced by far-field volcaniclastic deposits conveyed by turbid rivers from the active volcanoes in the north and east (Merapi, Merbabu, Sumbing, Sindoro), and by near-field clearwater runoff from the eroded Tertiary volcanic terrain (Menoreh Hills) in the south. Our findings support the interpretations of the Dutch artist W.O.J. Nieuwenkamp, who in 1932 visualized the edifice as an aquatic lotus symbol upon which the young Buddha was seated. Initially dismissed by scientists, these views are considerably more consistent with Buddhist cosmology than if Borobudur had never stood by a lake. Seasonal lakeshore fluctuations, although not detectable in the sediment record, probably played an important part in conferring on the temple a semi-aquatic character, especially towards the end of the annual rainy season within this "mesopotamian" environment. In this perspective, the sudden shift of the Borobudur-based Mataram government to East Java after 1006 AD may have been caused by chronic water-related diseases around Borobudur rather than any given volcanic hazard.