In the Netflix series he seems to have physical evidence backing up the age of said megalith, but since he seems to be a kook I wonder why his evidence doesn't hold up in the academic world? There have been some excavations, ultrasound images showcasing tombs and structures way older than the top layer, geological evidence (the stones came from an area that is across the current sea, so it must have been before the end of the last ice age and rising sea levels) and radiocarbon dating of some unspecified samples (I believe?).
That's what I remember. Curious about the answers.
Stumbled across this post kind of late, but here's a good faith answer:
I am not an expert in ground penetrating radar images (GPR) but what I do know are the basics -- but they're often misinterpreted (something that I actually learned I had some incorrect assumptions about when I started studying archaeology!). GPR doesn't work like perfect x-rays of the ground -- they bounce back measures of different densities in the ground. So -- the GPR maps they show definitely seem to indicate that there are areas of varying density in the hill, but until we actually dig into them, it's unclear if that's a sand deposit that's less dense than the surrounding dirt, or an empty room constructed by humans like Hancock claims. Would it be awesome if Indonesia had unlimited funds to excavate the entire hill? Maybe -- because then we could answer that question -- but we cannot conclude they are tombs/chambers etc. based on the radar alone. For example, in this study they map out the structures they suspect are there with GPR, then excavate to confirm: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7037787/. Need to ground truth the scans.
My biggest issue is with the dates they took from the cores. Unless I missed something, nowhere did they say *what* they were dating, they just said it was "dateable material" which for radiocarbon is a very vague term. Is it charcoal or animal bone from a human-made fire? Or is it just organic material that is dateable that is a natural part of the stratigraphy at the very bottom of the hill? Again, they need to dig a trench or test pit and establish that the dateable material is in fact human, cultural material.
Also, the geologist they feature in the Netflix documentary is being heavily promoted by the Indonesian president -- I think the concern is that there is some nationalist political motivation driving his work which has certainly been "a thing" in archaeology since forever. Other Indonesian archaeologists speak up against him in this link: https://www.smh.com.au/world/digging-for-the-truth-at-controversial-megalithic-site-20130726-2qphb.html.
I'm not a geologist so I can't speak to the origins of the basalt pillars.. I will also add, just as a very broad criticism, is that my gripe with Hancock is his continued insistence that hunter gatherers cant build big things, which is ironically a talking point of views of cultural evolution that "mainstream archaeology" threw away many years ago because it was so reductive.
While it isn't directly related to Gunung Padang, in case you haven't seen them yet you may also be interested in our earlier threads on Hancock, especially here by /u/kookingpot and here by /u/CommodoreCoCo.
The thing about conspiracy theory claims is that they can be made by the theorist with incredible ease and take a long time to debunk, so it is not unusually to find a particular point where none to very few people have addressed it. While it is tempting at an intellectual level to say "each claim must be addressed individually!" there becomes a point where someone is enough of a hack that the only sensible thing to do is discard what they've written wholesale. (In this case, things are double problematic because the findings never got published -- so there's no way for people to do scrutiny even if they want to -- only shared with the conspiracy theorists, which is a gigantic red flag.)