Evidences of Large pyramid-like structure predating 10,000 Year BP at Mount Padang, West Java, Indonesia: Applications of geological-geophysical methods to explore buried large archeological site

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SUMMARY: 3D AERIAL PHOTOGRAPHY OF GUNUNG PADANG PYRAMID AND INTERPRETATIONS OF ITS SUBSURFACE STRUCTURES BASED ON GPR, MULTI-CHANNEL RESISTIVITY , AND SEISMIC TOMOGRAPHY SURVEYS, CORE DRILLINGS, EXCAVATIONS, AND RADIO-CARBON DATING ANALYSIS
ABSTRACT Mount Padang archeological site has been known since late nineteen century as a megalithic complex that sits on top.Our studies proves that the structure does not cover just the top but also wrap around the slopes covering about 15 ha area at least.Comprehensive geophysical surveys combining ground penetration radar (GPR) and multi-channel resistivity methods, seismic tomography augmented by bore-holes coring data and archeological excavations, show further that the structures are not only superficial but rooted into greater depth.The structures are not built at once but consisting several layers from consecutive periods.The uppermost layer on the surface consists of horizontal piles of basaltic columnar rocks forming step-structure terraces and decorated by exotic arrangements of stand-up rock columns forming walls, paths and spaces.The second layer, which had been previously misinterpreted as natural rock formation, buried 1-3 meters beneath the ground surface, is a several-meter thick fills consisting of more compact and advance arrangement of similar columnar rocks in fine-grain matrix.The third layer is also artificial arrangement of rock fragments with various kinds that extent down to about 15 meter deep.The third layer sits on fractured, massive basaltic lava tongue.The survey also reveals evidences of large underground cavities or chambers.Results of preliminary radiocarbon dating indicates that the first layer was built around Cal BP 3,000 -3,500.The second layer was built around about Cal BP 7,500 -8300.The third layer was built prior to Cal.BP.9,500, and could be as old as Cal.BP.28,000.

Layer-2&3
Gunung Padang Megalithic site has been known since early 19 century but only recognized as ancient tombstone made of stacks of columnar-joint basaltic andesite on top of the mound.In fact, its exposure clearly shows that the youngest construction is built on top of an older, more sophisticated cultural rock layer.Besides, the morphology of the mound stands out as peculiarly much younger entity compared to the surrounded intensively steam-eroded, rough texture of the Tertiary volcanic rock complex.Hence, it deserves further investigations, particularly on what's lies beneath the megalithic site including suspected large chambers.
We use various near-surface geophysical methods including multi-channel resistivity, ground penetration radar (GPR), seismic tomography and geomagnetic coupled with core drilling and excavations.Hence, we are able to compare and verify the results of one method to anothe for better interpretations of subsurface structures.

MULTI-CHANNEL RESISTIVITY SURVEY
We use SuperSting R8 with 58 and 112 electrodes (www.agiusa.com);use various electrode spacing to have wide spectrum of resolutions and depth of penetrations in order to illuminate shallow and deeper objects.We conducted 3D resistivity survey particularly to scan suspected large underground chamber(s).A special thank to Mr. Andi Arief, who faithfully encourages and supports the research activities; without him, this study would have never happened.We are gratefull to Gen.Dr.Soesilo Bambang Yudhoyono (The former president of Indonesia) and his cabinets, Gen. Gatot Nurmantyo, Admiral Ade Sopandi, Mr. Dedy Mizwar (former Vice Governor of West Java), and Prof. M. Nuh.We appreciate our amazing field team who help us with zeal.We are indebted to all friends in TTRM and many others that can not be all listed here.

LAYER 1 (
BROWN) : Stone terraces of fresh columnar-joint rocks on top of thin soils cover the top and slopes of the mount (Age: Cal BP 3200 -4000), It can be modified at younger age

INDEX
8-m spacing electrode 2-D Slices of the 3D resistivity tomography B e fo re to p o g ra p h ic co rr e c ti o n GROUND PENETRATION RADARWe use SIR-2000 and 3000 of GSSI Units (www.geophysical.com)with various antenna including unshielded MLF, shielded 100Mhz and 250 Mhz; using various antenna frequency gives wide spectrum of resolution and depth of penetration for different purposes/targets.We conducted dozens of 2-D line survey CORE DRILLING were conducted at 7(seven) sites around the top.Two sites has drilling depths 30-33 meters, the rest is about G15-m depth .The logging as assisted by the GDA team (http://gda.co.id/)SEISMIC TOMOGRAPHY SURVEY The equipment and sofwares are developed by the Rock Fluid Imaging Lab(http://www.rock-fluid.com/).The seismic sources are generated by hammer, vibrator, and speciallydesign fire cracker. in Layer 1, 2, 3 are sampled for C-14 dating assuming they were derived from bio-organic activities after constructions.Most analysis are done by Accelerator Mass Spectrometry (AMS) technique at BETA Analytic (www.radiocarbon.com/)by (Former) President of Indonesia and his cabinet in February 2014