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Mohenjo-Daro: An Ancient Nuclear Mystery

If you’re not a nuclear physicist, nuclear physics is likely nothing more than a nebulous and abstract idea out of popular culture to you.  It’s easy to forgive someone for not understanding the finer points of induced fission or which elements make better nuclear fuel than others.  Frankly, the whole endeavour is better left to the experts…whenever possible.

I recently offered a post on spontaneous fission – that is, a naturally occurring nuclear reaction – and the astounding discovery made in 1972, wherein French physicist Francis Perrin found sixteen naturally occurring nuclear reactors in Central Africa that are 1.7 billion years old.  Some of you might be thinking that’s impossible.  To those people I simply point to the Sun and shake my head, though granted, that’s a slightly different kind of nuclear reaction.

The point is, it’s real.  Spontaneous fission happened, and it went on for several hundred thousand years.  There are those, however, who would have you believe that spontaneous, and even induced fission has happened many times on this little blue planet of ours over the millennia.  Though that story take a little longer to explain.

Mohenjo-Daro.  No, that’s not a mystical incantation, it’s the name of an ancient archaeological site in Sindh, Pakistan.  You may have heard of it, it’s a particularly interesting part of our history, and is connected to one of the most enigmatic lost cultures that has ever existed – The Indus Valley Civilization.

There is a lot of folklore and legend surrounding Mohenjo-Daro.  And while all of it is interesting, the most relevant bit to the current discussion is the fact that parts of the many ruins of this ancient village have undergone vitrification.  In other words, they’ve turned to glass.

Vitrification is the process by which sand, or more accurately, silica is super-heated and then cooled, which results in a glass-transition.  It’s the way all glass is made, in basic terms, though there’s a difference between deliberately fired glass for manufacturing (technically known as frit) and vitrified sand.  The latter type of glass consists of three categories:

·         Fulgurite, which is glass created via lightning strikes

·         Tekkite, which is formed from the heat generated by meteor strikes

·         And trinitite, which is the glass that results from nuclear detonations.

Now, from the opening of this post, you can probably already tell which one is popularly thought to be found at Mohenjo-Daro.  The only real difference between those three categories of vitrified sand is the different heat sources that make them.  Other than a tendency for trinitite to be radioactive (Duh!), samples of each are pretty much the same compositionally.  Silicon dioxide, which is the most common element in sand around the world, melts at roughly 1,700 degrees Celsius, so any one of those methods can get the job done.  But if there were a competition, the clear winner would be a nuclear detonation.  The heat generated through a nuclear blast can be greater than 10 million Kelvins or 9,999,726.85 degrees Celsius.[1]  By comparison, the surface of the Sun is only 5,778 Kelvins.

Yeah, that’s pretty hot.  In fact, it’s hot enough to flash-melt pure silica into glass instantly.  So the Mohenjo-Daro vitrified ruins were made by one of three potential events, it seems.  A series of major lightning strikes, a meteor strike (or perhaps more than one), or a nuclear detonation.

The Indus Valley isn’t the only place to boast vitrification mysteries though.

Scotland has over 70 examples of what are known as Vitrified Forts, such as Dun Mac Sniachan.  These are crude encampments from both the Iron Age and Early Medieval period with stone-pile walls, usually situated in easily defended formations.  The outer walls of these forts have been heat treated, so to speak, resulting in whole sections of wall where stone and brick have melted into a glass facade.  They are wondrous, and in most cases they are quite beautiful, and they make up a collection of vitrified forts that dot the landscape throughout Great Brittan.

There are other places too, such as Çatalhöyük in the southern Anatoli region of Turkey, and Alalakh in Turkey’s Hatay Province, and even the Seven Cities of Cibola in Ecuador.

You might be getting the wrong impression though.  As mentioned, it’s commonly believed that one of the three potential methods of vitrification was responsible for all of these sites, with a conspiratorial bent toward some form of nuclear energy, whether that be detonations or a fission reactor of some kind.  But this isn’t necessarily the case, nor is it likely.

Remember above, when I told you that silicone dioxide melts at around 1,700 degree Celsius?  A flame fed by natural gas can easily reach 1,600 degrees Celsius, and a bonfire with mixed fuels can approach 1,200 degrees, especially if extremely dry wood is used, perhaps pinion pine.[2]  Both of those examples are of open flame fires, but what if that flame was enclosed?  Perhaps, within a stone structure where the heat would be trapped, reflected, and amplified by the stone?  Internal structure fires, like we see in today’s buildings, can easily exceed 3,000 degrees Celsius, so it’s not unreasonable to think that temperatures sufficient to reduce stone to glass could have been achieved in Mohenjo-Daro and other locations without the use of nuclear power.

That isn’t to say that some catastrophic event didn’t take place in the Indus Valley of the time; a war, a religious or ethnic cleansing, or some really wild parties that got out of hand.  But it isn’t likely that the vitrification was achieved through a nuclear reaction of some kind, whilst leaving no traces of radiation or fission products in the surrounding environment, and most conspicuously, without levelling the entire city.

In the case of the Vitrified Forts of Scotland and elsewhere, it is believed by the experts, that it was indeed wild parties that caused the destruction, sort of.  Most archaeologists assert that these locations were deliberately destroyed by fire, either by successful invaders or by the inhabitants as a part of a ritual closing of the facility, as it were. (Ralston 2006, 143-63)

It seems, and this is purely speculative, that the parties who wish to further the argument that these examples of ancient vitrification are the result of a lost or perhaps natural nuclear process, are simply taking advantage of the popular familiarity, and simultaneous ignorance, that we all possess on the topic of nuclear physics.  In reality there are simpler explanations to be considered, even though the alternatives may be more exciting.

[1] Glenn Elert. Temperature of a Nuclear Explosion – The Physics Factbook

[2] J.T. Barett. How Hot Is a Bonfire? Demand Media


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  1. Something Else
    While I agree that the “nuclear hypothesis” doesn’t stand up against evidence on the ground(lack of residual radioactivity, lack of destruction, as you said), I don’t see how the “bonfires hypothesis” does any better. For instance, while it is true that an enclosed fire can approach the temps necessary, the areas of vitrification are a little large for that, it seems to me. How would such widespread areas have been subjected to an enclosed, furnace-like fire?

    I think there must be some other answer. One thing I considered was the passage of a large meteor through the atmosphere at an extremely oblique angle. Such an event could certainly provide the necessary heat over large areas, would not leave much residual radiation, and–if the angle was really extreme–might even have passed through the atmosphere without ever actually impacting, and continued on out into space again. This would explain the lack of destruction.

    Pure speculation, of course.

    1. Rome Burning
      Why can’t a fire be widespread?

      Where is the meteorite evidence?

      For example the Tunguska event (please don’t say UFO) flattened 80 million trees over an area of 2,150 square kilometres with the shock wave from the blast would have measured 5.0 on the Richter scale. Forget about vitrification as nothing would be left standing as well the temperature wasn’t high enough…flattened trees, not missing vaporised trees.


  2. Perhaps Aluminothermic Reaction
    There is perhaps another explanation, more rooted in geology and metallurgy. I have done numerous experiments in mineral processing of different metal ores and have witnessed some interesting phenomena with different metal oxides (ie silicon dioxide) and a “thermite” type reaction. We are largely familiar with the traditional iron and aluminum thermite reaction, but many other metal oxides react in a similar way (see this website for a basic primer: This is an extremely exothermic reaction and I have seen glass slag formed as part of the result.

    I have long been interested in ancient knowledge of metallurgy and alchemical processes, now “lost” to time. Can’t help but wonder if this basic, easily performed reaction wasn’t the source of some of these mysteries. Archaeologists are too quick to chalk things up to religion, etc. and don’t have the perspective of engineering and material science to be able to see all possibilities.

    Would be interesting to learn of what sort of ancient mining activity is nearby these different sites where vitrified glass is found. Could be a by-product of extractive metallurgy?

    1. Interesting hypothesis
      That’s a very interesting hypothesis, an idea I hadn’t considered. As you said, there are many minerals that react that way, and though a great deal of heat is produced, they don’t offer any other effect (i.e. shock waves, radiation, etc.)

      Thank you, I’ll be looking into this.

  3. Coming in late and without
    Coming in late and without ANY knowledge of the sciences involved. Having said that I may as well go full hog and embarrass myself further. An unfounded thought entered my mind after reading this. It appears to be well known there was a substance called Greek fire. We lost the recipe for it so composition is not known (Only what I have read, I could be wrong) Could there have been something along the lines of a forgotten weapon used at these sites?

  4. I suspect wizard thrown
    I suspect wizard thrown ligtning bolts.

    On a more serious note, the elevated fortifications, presumably containing a fair amount of iron, might be more likely to be struck by lightning than other structures in the vicinity.

  5. Other factors
    Aren’t there other factors involved in the mystery of Mohenjo Daro, though? Like the notion that the human remains discovered in the city had the appearance of having died in a very sudden and unexpected manner?

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