Glass Castles: The Mystery of Scotland's Vitrified Forts

[@julesdingle]

AMAZING COMMENTS thank you- [and yeah probably dragons ] As with many film projects by the time they are finished I have developed my ideas more fully- I'm not sure if its clear in the video but I conclude that whilst discovery of vitrification might have been accidental the architectural skills were developed to make a rubble wall more pleasing and durable. Modern science has failed to reproduce the results - but given a big enough budget I would suggest that a timber framing filled with rubble could be fused with charcoal being introduced in quantity with the rubble infill and the wall insulated in turf. what do think? And if you have had experience with dry stone walling how would you recreate these glass walls?

[@freeforester1717]

The means of replication was found by Armstrong and Aldrin in July 1969 on the surface of the moon, as described by former NASA scientists involved with the interpretation of the samples brought home by the astronauts of the Apollo🤔 11 mission. It is well documented that the sudden mass extinction of the North American megafauna species ( along with the apparent absence of human activity on the North American continent for around another thousand years thereafter) appears to have occurred at the time of the mat of carbon and microspherules and tektite glass of Solar origin, i.e. no remains were found above the layer of Solar origin. Radioactive isotopes and the absence of gas bubbles along with the form of these beads point to this, and confirmation of presence of same tektites has since been made on the surface of Mars as well as the Moon, where no atmospheric decay or disturbance has occurred ( - the real reason the mission was sent to the moon, to conform what was already suspected. Diehold Foundation, Series 4, Doug Vogt: watch them all. Man made vitrification did not occur. From within view of Tap o' Noth, Aberdeenshire.

[@rosskstar]

Dragon's Breath no doubt

[@blessedthistle1.414]

I would use lightning to fuse the rock, as I could use a conductive rock/electrolyte paste and a fancy lighting rod.

[@JohhnyB82]

There is evidence of vitrification at the sites of Sodom and Gomorrah, I don't remember the proper name. The theory is that a meteor caused it. I can not recall what the documentary was, but it was a legitimate source like Nova.

[@JoesWebPresence]

@12:35 "The difficulty in achieving vitrification further suggests that it was no haphazard event, but a planned technique, requiring careful preparation and use of fuel . . " I watched the mysterious worlds episode too. I remember that the calculation for fuel was 40,000 tons of oak, and that it would have to be replenished during the process, so yes, quite an undertaking. Try carrying a fencepost up Tap O Noth, and you'll get an idea of the scale of this project. Achieving those temperatures is cutting edge technology for the iron age, and while charcoal is necessary for achieving those temps in the forge, insulating such a great fire so it heats the rock would build these temps over time. Fanning it is not necessary due to the wind, but conssideration to how the air currents would work must have been key to the whole process. My guess is a vortex was achieved, maybe section by section. Picture a circle of rocket stoves made of stone, with earth packed round them and timbers piled high into the top so they'll fall down into the chimney and feed the fire as it burns. It would have looked like a massive fire tornado on the horizon, probably lasting many days. Getting 40,000 tons of fuel up a hill that size isn't difficult. It's a monumental task, way harder than building Gastonbury Tor, or moving the sarcen stones to Stonehenge. It had to be, constructed to draw its own air, feed its own fuel and store its own heat, then lit, probably in multiple places in a particular sequence. Imagine what it looked like all ready to go! My guess is it was probably dawbed with mud or clay in order to hold in the heat. Given a big enough budget, can we do it today? Yeah probably, but we have computer simulations for this now. I'd love to encourage anyone with the computer skills to give it a go. It would be an awesome virtual reality spectacle in the night sky, AND it could show us how they did it and what it looked like when it was new!

[@dmcclure-ky6sc]

For the IRON AGE to take place, the technology of creating large quantities of charcoal from mounds of oak logs covered in turf with a weeks-long controlled had to be developed. A similar technique was then developed for smelting iron ore by placing the charcoal and crushed ore inside an earthen kiln, and creating a very hot fire with a forced air draft. From the melted contents of the kiln, the lower melting silicate minerals would first be drawn out in a crude glassy slag, and then the remaining iron bits would congeal into a so called "bloom" which was then further worked into a solid mass of iron. Thus the techniques of the earthen kiln and controlled fire had already been developed. Now, glassy slag and more charcoal were readily available materials to the builders. One might imaging that after observing molten slag glass drained from a smelter fusing together rubble around the base of the smelter, the thought arose that this same slag material might be re-melted to intentionally fuse a mass of masonry pieces together, with a lot of very careful planning. Therefore, an empirically developed mixture of crushed previously melted slag and charcoal fuel could have been placed ( as a dry mortar-like infill) between the dry laid stones of the fort wall during its initial construction. Then similar to the charcoal kiln, a turf covering could allow controlled airflow to later fire the core of the wall. A firing to briefly re-melt the crushed slag, allowing a thin layer of melt to bonds adjacent wall stones would be sufficient; thus forming an intermittent glass "mortar" connecting the stones into an immovable mass. Drainage saps in the mass left by burnt charcoal might have reduced the chances of frost later cracking the wall apart. Quite likely, the exterior turf cladding would simply have been left in place in the finished product, as they were in so many other dry stone wall constructions. Sections of un-fired wall constructed as above still serve their immediate defensive function, which would allow the carefully controlled firing process to take place at a later date as the availability of time and skilled individuals allowed. While this comment is submitted as informed speculation only, the various components are well established historically, and the leap of using the waste slag for a such higher purpose is exactly the kind of idea that might present itself to someone who had already mastered the task of extracting and using the iron portion of the smelter contents.

[@julesdingle]

silica rich slag that would also have some lime left in it would make for a good flux mixed in with the fuel - the silica would also react with feldspar in granite to create a glassy substance the archeologists of 1980 should have perhaps consulted chemists and those familiar with smelting to build a better experiment the picts were clearly smart and could have borrowed techniques from iron making, something done for 100s of years before these forts were constructed good call

[@duncanspiers8855]

I read about this phenomenon and the then prevailing explanation concerning charcoal in the 1970s. At the time, I was looking at a vitrified fort in Peebleshire. I didn't know it was still a mystery today?

[@lettersquash]

@@julesdingle What, has nobody inspected the surfaces of the fused rocks? Surely geochemists would be able to tell if there's a layer of material of a different content without much difficulty. This idea from dmclure, does seem to be a good one, that something with a lower melting point than the general rock might have been used as a mortar. This would drastically reduce the amount of fuel required, which in other suggested methods seems prohibitive. As well as bi-products from earlier smelting, it's possible that naturally occuring materials might have been found. Would silica-rich sand melt more easily, e.g. from beaches? If it's prohibitively expensive in fuel to do this deliberately, it's not going to happen through siege warfare, retribution or scuppering your own fort so nobody else can have it / it gets stronger. Did you say that was the consensus view, because it's nuts! Interesting video, but you could do with better sound - the commentary is very bassy and the level rather changeable, making it a little difficult to hear.

[@joyreinhardt7621]

Have you 'read/heard' how the fallen angels came to people, and taught them things like tis ? See the book of 'Enoch' !

[@Forest-iv5vm]

This could even build upon the theory that a survivor of a siege saw the vitrification of the walls. If they were familiar with the slag of a kiln, it becomes quite easy to connect the dots. If there’s evidence of layering in the walls, one might argue a smith does their work for a year and piles all their slag in a section of the wall, builds a kiln over it and melts it in, then a fresh layer of stone is placed on top and another year of slag is piled up on it.

[@TheMadmacs]

i suspect they surrounded the walls with greggs sausage rolls, which contain more heat for longer than fuel rods at a power station.

[@iainmcfadyen9197]

Stopit, pmsl

[@TheMadmacs]

@@iainmcfadyen9197 hehe i forgot i said that.

[@anthonypearson3806]

MacGREGGors sausage rolls --- surely ? . . From Sausageroll Street, Glasgow.

[@TheMadmacs]

@@anthonypearson3806 ... come to glasgow, the streets are paved with greggs sausage rolls.

[@johnedwards1685]

I dispute your hypothesis! They clearly deep-fried those stones in batter, hence the unusual appearance. My own experiments with deep-fried Mars Bars and lemon drizzle cake support my proposition.

[@brazilchem]

Dragons, obviously.

[@lorenstribling6096]

The ancient castles are fascinating but the real beauty here is Scotland itself.

[@margomoore4527]

In childhood, I recall reading a tale of a young hero attempting to climb a glass tower riding his horse. It seemed impossible. But a fort with vitrified walls-maybe. I figured sooner or later some remnants of a glass tower would show up. Glad they have!

[@caoimhekeohane2015]

Brillliant to see a deep dive into vitrification! I live near Inverness so this was great to watch. Many thanks!

[@Peter-MH]

Very interesting! It seems things during the Iron Age, and even earlier, were much more sophisticated and organised than generally thought.

[@circumnavigator8177]

We do not give ancient peoples nearly enough credit. Wish I could have seen some of these while I was over there. Great work. Awesome that you've been able to document so many sites

[@elultimopujilense]

Those views of Scotland are just majestic! What a beautiful country!

[@julesdingle]

check my other videos out if you want a taste of the extraordinary beauty of the country.

[@elultimopujilense]

@@julesdingle I will definitely do that! thanks!

[@bazdaniels7420]

It has been proposed that the 6th century comet strike may have vitrified these forts, super-heating the atmosphere overhead as it passed over the British Isles.

[@addersbowman]

As a glass maker who melts sand into glass every day, i can say that you would need to achieve temperatures of over 1800C to vitrifie rock. This is simply not possible by around 1000C using the techniques suggested here.

[@julesdingle]

true for sand as it is mostly silica dioxide - granite however has more feldspar and the melting point is about 1200 C - close to what can be achieved with charcoal over 24 hours, and with a flux like sea shells and wood ash could reduce the melting point to 1,000 C at least to weld the lumps together for sandstone conglomerate the high content of clays mixed in would also act as flux reducing the temperature needed What is lacking from the 1980 'practical' archeologists is some basic understanding someone like your self could offer

[@addersbowman]

@@julesdingle also I seriously doubt if any of the Celtic peoples had any knowledge of fluxes. Sand being tiny grains can be mixed with fluxing agents such as potash to reduce the melting temperature. As for temperature gained by burning wood, even in a controlled small furnace, the amount of charcoal/ wood required to gain those temperatures is immense. We are building a charcoal fired furnace to melt a tiny bit of glass later this year, the logistics getting enough fuel is difficult even on this scale.

[@julesdingle]

@addersbowman fluxes were known for 100s of years before these forts were built as part of iron smelting but yes materials required are considerable but not impossible- for every tonne of granite about 150kg-200kg of oak charcoal, 75 kg wood ash, 25kg of either broken shells or iron slag The key would have been insulation to maintain a 24 constant burn In the walls visible in the video you can see the rock has been fused together, the rocks were not melted to glass I would love to build a test fire again but the logistics are rather expensive for my budget!

[@peterrose5373]

It looks more sintered than really vitrified to me. And I wonder if they coated or mortared the rock with some sort of clay or other material that lowered the melting point on the surface?

[@KAL5370]

Greek Fire in the rain.

[@agnesboyd-t3q]

I'm 69 and remember watching the A.C.Clark video and he said something along the lines "That it would take half the trees in Scotland to replicate the largest of the hillforts , I have a 50x 20 x20 yard area of spare ground surrounded by wooden fences without access and during summer it is one massive battle for territory between the wild growth and weeds and even a few fast growing trees have popped up ,Glasgow city council come round every 4 or 6 years and excavate the area .I wonder what it was like when you looked down from the top of "Tap o North" a few thousand years ago And who excavated all the land in Scotland & Britain Europe for farming use ? And where did they burn all the combustible weeds and wild bush growth Etc ?

[@hendrikvanleeuwen9110]

You wouldnt get the heat from simply burning brush.

[@agnesboyd-t3q]

@@hendrikvanleeuwen9110 Hi What i was thinking is that when this vitrification process structure was finalised between 3 and 4 thousand years ago how long did it take how many workers and how much stuff was burnt taking into account they did not have engine powered vehicle's to transport combustibles

[@hendrikvanleeuwen9110]

@@agnesboyd-t3q charcoal making was definitely a major source of deforestation in bronze and iron age Europe and was sometimes transported for metal working. So it isn't impossible that it was done as part of the fort construction. Also I think the 'half the forests of Scotland' assertion is probably incorrect.

[@greywolf9292]

Despite the fact that Scotland resembled one huge forest back in those days, its more likely that if this was a deliberate construction method that Peat, Heather and Gorse were thevfuel for the fire. However, if we view them as ruins, which they pretty much mostly are, perhaps we should give more credit to local legend. Which says that an invading King of giant stature weilding a rod which exuded lightening, went on the rampage destroying all the forts. Similar stone structures destroyed and turned to glass were found in India, the heat required to melt the stone being described as being likened to that of a nuclear bomb. History is destroyed and rewritten with every new century and more often manufactured to promote the official narrative. Perhaps there's nothing new under the Sun, we just rinse, reset and repeat.

[@itzakpoelzig330]

Likewise, vitrification of buildings has been found in Ireland, France, Germany, Scandinavia, Bolivia, and Peru. I have no doubt that it's a worldwide phenomenon, and that the explanation is very different than any documentary will ever tell us. Where can I learn more about the local legend of the giant king? Do you remember his name?

[@greywolf9292]

@itzakpoelzig330 Thanks for your reply, sadly I don't remember the giants name. All I remember is I discovered this whilst researching videos about vitrified forts here on KZbin. I also came across another legend regarding another King, who was able to fly huge "charged stones" like a magic carpet, from one end of the UK to the other following ley lines. Sadly he met his demise when one such stone fell out of the sky, somewhere North of London. It's believed the stones were charged using a type of Faraday cage ( it has a name I can't remember) built of wood, stone and turf. The book went on to say that the building of such " devices" is illegal in the UK.

[@luxuriousfir]

Melted kingdoms all throughout our realm.

[@kennyhagan5781]

I saw that show! I was just starting my junior year in high school and I was fascinated by the fact that the stones were fused by heat. I even went to the trouble of asking both my history and chemistry teachers how they thought it might have been accomplished. Thanks for bringing back some interesting memories.

[@jimjolly4560]

I visited the vitrified fort of Dun Skeig. Given its location, the extra effort in bringing the wood required to burn it after capture would seem unnecessary, whereas vitrification as a means of binding small stones and strengthening an otherwise unstable structure makes a lot of sense. Fascinating video, thanks!

[@ace__7063]

Thank you for talking about this topic I have been deeply fascinated with this subject for a while now and thought it was mad how little people know about this, I am from Scotland and almost no one knows about this.

[@PeaceJourney...]

Camelot was said to have glass walls. Love to see the evidence of a possibility, thank you for sharing 💙

[@josefsterling5462]

I have a theory about the whole sword in the stone thing, we take it literally but what if it was relating to actual iron production from ore, pulling a sword from a stone, apparently king Uther wasn't a great leader and Merlin knew this so instigated a takeover, usurping the throne and putting Uther's son Arthur on it while teaching him not the be the man his father was 🤔🤔 if he was real, as a "magician" he would have probably known about alchemy etc and passed some of this in to his "apprentice".....

[@PeaceJourney...]

@josefsterling5462 interesting, and makes sense of the magick

[@clayblaze1327]

@@josefsterling5462I’ve never thought about it that way, interesting theory

[@josefsterling5462]

@@clayblaze1327 alot of history is labeled as mythology by people who can't decipher the symbolism, it's all theory as none is were there to say any different, people spend their entire lives earning qualifications that give them the impression they have rights above all others to comment on certain subjects etc, people rely on "facts"(commonly agreed opinions) instead of learning to understand the truth in things, the truth needs no evidence to exist while fact relys on it lol it's all interesting either way but to some the truth isn't as interesting as the fantasies that obscure it

[@PhatChic]

another fascinating insight into a subject matter that was alien to me. you really would have been the coolest teacher in school

[@gargoyle2585]

This is absolute quackery - We acting like there was no conflagration from comets and lightning that vitrified all this stone... The Earth is both cathode and anode.. everything needs a ground - the hills being closest to the sky - zap...! we could look into the work of Noah Webster for a start... Recorded history. Zap Zappity Zap and maybe some research into atmospheric conditions of the past? Again, recorded. 2025 talkin bout lightin fires against walls like we don't know it's the JUICE that's missing, the POWER! What turns sand to glass people?? extrapolate to bloody hilltop forts with bigger lightning than you've ever known existed!! So big it flows - for so long it melts all in it's path - carves new channels - creates caves - Ever seen a Lichtenberg Pattern??? cmon ppl wake uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuup - G'mornin 😁

[@davidnorwich3771]

Wow the mysteries of Scotland! Glass walls. Who would have though that someone in the distant past would come up with that idea? I loved this video and also the comments.

[@patrickbarrett5650]

I love the Scots Pines, at sunset the trunks glow with a unique red hue.

[@GordonDonaldson-v1c]

" . . . unique red hue . . ." patrickbarrett5650, you have never seen a Rhine Valley pine, then?

[@pks15032]

Your sentences regarding Clarke in the 80s were exactly mine back then too. I bet we watched the original same airing. I was scrolling through YT and saw vitrified forte and had to watch. Superbly interesting, thanks.

[@hammyh1165]

My friend has a small one on his farm , it is believed to have been Pictish then used by the Romans.

[@DarkPeaksRadio]

I agree with others that gorse would have played a major part in the process but the biggest factor is wind. Stand on any hillside in Scotland and feel the force of the biggest natural bellows possible

[@ZacLowing]

It was a thick forest back then, not barren land like today.

[@johncastro7372]

Certain chemical reactions happen with higher oxygen levels. They would have realized the tip of a mountain produced better steel and why!

[@geolyn]

This was new to me. How fascinating! Your photography is gorgeous too.

[@timflatus]

Excellent. More Hill-forts and prehistoric buildings please!

[@johnakyle5908]

I'm near Dun Deardail Fort in Glen Nevis and always have found it worth a visit , such a great setting, commanding views down the Glen .I was unaware there were so many of these forts in Scotland.

[@neilreynolds3858]

Charles Fort wrote about them around 1930 and that was the last time I heard anything about them.

[@dr.froghopper6711]

Those pesky dragons get a little carried away during the breeding season.

[@lindafarnes486]

This is a very interesting re-visit. Apparently, although they were thought to be unique to Scotland, they have been found across Europe. Also, the time frame for use is Iron Age to early medieval. It would be interesting to see more research. Wikipedia said it weakened the walls, rather than strengthened. But maybe the builders thought it strengthened the structure. Maybe it's more complicated than that? Seems like a lot of work to go to just be decommissioning an old fort. Your comments indicate there might have been advantages. Of course looking impressive has importance.

[@robinaart72]

very interesting vid. I used to be a drystone waller - this got me thinking...if the majority of stone available on site was small, rubble sized pieces, then it would be difficult to make a secure defensive wall - rubble is important to drystone walls of course - mainly for the infill - but for a good strong wall, the bigger the stone, the better....which could explain the vitrification - they would 'create' the large stones needed using this technique, and use the smaller rubble for infill. It's possible they built a rubble wall first, and then vitrified the face. I'm thinking that making use of trees in the area and using horses or cattle to drag the trunks up to the top to make the fire would have been easier than transporting hundreds of tons of large stone from the base of the hill - it could be that the smaller stones at the top were that size due to millenia of frost, braking down the large stones into rubble. Just some thoughts.

[@willkrummeck]

Yeah im thinking maybe they use volcanic ash

[@willkrummeck]

Then you dont need heat to make glass, so if someone did thing sections we can confirm.

[@willkrummeck]

Very nice project for honour or master split up. Interdepartmental architecture, geology and cement engineers.

[@selmandr]

In 536 A.D a large bolide comet crossed from Norway to Scotland and England and probably hit in Brazil or Bolivia. This comet was probably Justinian's comet and was mentioned by Geoffrey of Monmouth. Many sources including Oxford University discuss this. Excavations also show that the bolide burned up a large swath of Scotland, England and probably a part of Wales. And this is about the time wine production in Scotland ceased.

[@brucemacallan6831]

Alan Wilson & Baram Blackett spoke of this.

[@WilliamH490]

Exactly

[@Bob-h3n]

How did it burn Scotland and England? Radiant heat? Are you sure?😂

[@loke6664]

And it just vitrified these particular castles? No, this was made on purpose when they were built. They were all built within a couple of 100s years, all Pictish and they were likely inspired by the iron working techniques of the time, the product is similar to a bloom. The Swedish experiment shows that by isolating with peat, you will get vitrification and they likely also used the wind to a bellow like effect. While we don't know exactly how they set things up, the whole thing is not unfeasible. That a comer or meteor could create such an effect on specific different locations all from the same time makes little sense, if it had hit a specific fort like the Tunguska incident, that might have made some sense but just by passing over would be pure magic. If it would have passed that close we would talk about maybe a 100 meters above and if that was the case, gravity would hardly have allowed it to travel all the way to South America before hitting the earth. The locations are not in a straight path either and it would point straight south, not west. while covering a large area but just specifically hillforts made by Picts. It makes as little sense as aliens with lasers having a war with the Picts. This was not something that destroyed the forts but something that happened when they were constructed.

[@Bob-h3n]

@loke6664 Comets travel at thousands of miles a minute, to project that much heat over that much distance that quickly it would need to be hotter than the core of a sun. This guy has the belltower packed full of bats.

[@davidprocter3578]

I would just like to say after reading through the comments that some wonderfully considered points been raised, a great pity the internet was not around in 1980 the experiment might have taken on a very different prospect. Also some great humourists out there had quite a laugh.

[@alaindubois1505]

Born in Scotland, but without a memory, I struggle now with Australian heat and a divided comunity. I welcome seeing a real human in a real environment. I imagined seeing glass castles, and accept that vitrification may just mean a bonding or small stoney elements. i was used to seeing megalithic structures from very ancient times on KZbin with the latest information being about some of Stonehenge coming from Scotland. I'm now with iatrogenic pharmaceutical company-induced life endangering health consitions. I constantly cross the Queensland/NSW state border in order to access the medical treatment I need. I'm losing eyesight and with narcolepsy, I find travel difficult in a country intent in reducing average lifespans as railways are destroyed, and people die on country roads. Do you have KZbin videos of former rail lines. Brisbane wuth a population in the earky 1900s had nire raiway stations then - than now with over 1.5 million residents. Bitumin covers much more land surface preventing rain to penetrate into the water tables. To save Earth - and let people freely access their environment, we may even have to go underground, in such deadly hot places like Australia. If New Zealand had passenger rail on again, when the rest of all I know in Australia have died, I would think of going there - if I could.

[@julesdingle]

I occasionally do videos following old railway lines and on occasion have some on ones that are romantic check out my play lists I have other subscribers with failing eye sight and who cannot travel as I do but happy for others to live vicariously through my videos best of luck

[@jeffheiner]

Thank you for sharing such amazing history with such an interesting and more compelling perspective!

[@GaryMcKinnonUFO]

I remember reading that Gorse would be a good candidate due to the very high temperatures that can be created.

[@rickanderson6540]

Probably the best example of a Vitrified Fort in Scotland, it is just a few miles south of where I now sit. The Fort is found on the southern most headland of this isle, the Isle of Bute.

[@julesdingle]

interesting, will check that out

[@richardclegg7846]

I'll visit this year 👍

[@incongra]

Are you aware that a vitrification experiment was carried out in the industrial setting of Plean Colliery, between Stirling and Falkirk, by V Gordon Childe in 1937. A section of wall was built interspersed with railway sleepers. Photos exist

[@julesdingle]

thanks for the information, a part 2 is to this story is forming perhaps looking at the methods, early attempts to recreate it are very interesting

[@jamesm9560]

Hard work. Great job!

[@brendansmith8167]

Oh! Is this was Tolkien drew on to describe the walls built by the Númenorians?

[@mr.e170]

Perhaps you might consider that the dates could be wrong and these castles could be much older, vitrified by the younger dryas impact hypothesis. 🥶🔥🤷🏻‍♂️ it would explain why nobody can recreate the methodology and provide more intense heat for almost instant vitrification. Dates could have been based on evidence of later habitation of the area rather than evidence of original construction.

[@DarkPeaksRadio]

I'm in Sheffield and we have a vitrified iron age fort at Wincobank. I believe it's the southernest one in Britain. You can clearly see it at various parts in the ramparts.

[@julesdingle]

thanks for the tip, Wincobank would predate many Scottish forts, the archeologists presume accidental vitrification in a pre Roman tribal conflict, but if it was deliberate then that would make it an interesting site to investigate [I feel a part 2 is in the making] And yes forced air would be essential - designing the burn to take advantage of the prevailing wind. gorse as I mentioned is too fast burning required for the 24 hour burn required to melt rock but a gorse fire at both the fire box end and the vent would create a powerful air draw through the wall

[@leonbarnes1402]

@@julesdingle gorse burns very hot though, gorse to get the heat in the fire and the long burn duration of oak could maintain the intial heat given enough insulation

[@loke6664]

@@julesdingle The key must lie in the iron working on the time, the bloom technique creates something that looks just like this. I would bet they used peat to isolate while had something funneling the wind like a bellows. I have a feeling they probably used coal instead of wood like in iron working too, you get higher temperatures for longer that way. The whole thing was clearly done during construction and not an accidental effect during their destruction. They all seems to have been built by Picts during a relatively short period. Like any other lost technology (Greek fire comes to mind), it is an interesting topic. I do think talking with an expert on iron age kilns would probably help.

[@freeforester1717]

Consider the nature of our planet - at some point on its circumference the impact from a Solar ejection eventually ‘misses’ the edge of the part of the sphere facing the Sun. See Diehold Foundation, series 4 with Doug Vogt; when the US authorities amend their Statute S4488 on existential threats to its citizens on the suggestion of one man’s lifetime research, you may surmise that they knew that he knew that they knew that he knew more than they did. Series 4 - watch them all. Also the books The Cycle of Cosmic Catastrophes by Firestone, West and Warwick-Smith, and ‘Catclysm!’ by Allen and Delair, both of which detail the nature of the Solar strike. Consider also Anthony Perrat’s interpretations of petroglyphs and plasma ejections (there’s one up on Kinder Scout), and take a look at the ferocity of a jet fighter’s afterburner when those ‘diamonds’ form in the exhaust wake. HNY from near Tap o’ Noth 👍🏻

[@Flying0Dismount]

Of course, you have ignored the obvious solution, that the Scottish people are actually aliens from another planet that employed the last of their extraterrestrial technology to create defensive structures after the were stranded here on earth... And how else do you explain that accent... 😝

[@peterdorninbalance]

This is the first time I've heard of glass castles. A very interesting thing. Your thoughts on the subject are also very exciting. I would like to raise the question of whether the glazing of the stone was actually done intentionally, or perhaps it was more "accidental", for example in a fire? It has already been proven that hilltop fortresses have often fallen victim to fire (and were not rebuilt). The effort required to change the stone's composition is so immense in terms of the amount of work, the amount of materials and their procurement that it is disproportionate to the mundane use of a simple, hilltop-fortified settlement. But I could very well imagine such an effort for a representative prince's palace or royal residence. Nevertheless, thank you very much for this short, very exciting video about the Scottish hilltop settlements with their very unusual masonry!

[@festerallday]

My guess would be that they used temporary, or portable, forges to smelt their iron. They could use the slag as a reinforcement to the walls

[@johncamp2567]

Fascinating, well-researched, and nicely presented. Beautiful photography!! (new subscriber, Virginia)

[@fredwood1490]

Something to think about: Many of these places are built on old lava domes, which can be heated by intense fire, from charcoal fires and will melt. I actually did that with a cutting torch on the island of Puerto Rico, thinking I would make sand but made glass instead. Lava rock and lava sand can be melted easily!

[@tamlynburleigh9267]

Thanks. First time I’ve heard of this.

[@TheSilmarillian]

Fascinating indeed new sub here greetings from Australia.

[@TheErichill]

There are vitrified temples at My Son (me sun) i n Vietnam built by the Cham people in the Khmer style between the 4th and 13th centuries. These are made of fired brick, but then a temporary kiln was built around the finished structure to give it a glassy finish. I always assumed the purpose was simply to be shiny.

[@mchazy7775]

Dunnydeer castle at Insch not too far from Tap O Noth was also built on the remains of a small vitrified fort if I recall correctly

[@christophercoleman6596]

Smelting iron in a forge, where heat & flame can be controlled, does not explain how large stone forts were literally melted by intense heat.

[@peterrose5373]

I'm pretty sure the melting was less complete than everyone is imagining.

[@aprilbrown53]

I wonder if this is how the Glass Mountain element made its way into faerie lore.

[@angellabutler6449]

They used to call maybe giants fairy people because they had fair hair.

[@prairrie]

I enjoyed this video and have visited two of the hill forts and live in a,village with a famous hillfort on Tuesday firth.

[@stevesloan6775]

I seen a fully glass castle in a documentary on Ireland about 30 years ago. The castle was one huge smooth glass structure. It was perched right on the edge of a huge cliff overlooking the Irish Sea in the north east coast of Ireland. When I first got the internet I tried to find information on the castle and I couldn’t find one thing on the castle. I’d love to know if anyone has heard of the castle in question.

[@itzakpoelzig330]

No, but that sounds amazing. Can you remember anything more about the documentary?

[@Dripfed]

It's aliens......😂 Never heard of this before, now I've gone down a rabbit hole because of your work in making this documentary. Many thanks for this.

[@permabroeelco8155]

There’s a story about a hilltop castle near Eerde, in the Dutch province of Overijssel. This early castle was built entirely of oak wood. When it was finally burned, the fire lasted for a month. This was not a timber laced wall, like many Celtic forts had, but you can imagine a hilltop timber laced fort in a strong wind can create immense heat, especially when the timber was oakwood. I don’t know any fort in which the vitrification has a defendable height or structure, like if it was purposely designed, but I can imagine that wham you rebuild an old fort, you could incorporate the vitrifications.

[@KaioKenX8999]

Was Darth Vader’s English cousin hired to narrate this?

[@julesdingle]

check out my early videos and my voice is better, this was the third take and as good as it got. I picked up covid in Germany filming last October and my voice hasn't been the same since.. so here is hoping incidentally I film, write, edit and narrate all my videos with the odd exception

[@ThomiX0.0]

There does not exist a method which could cause any kind of bedrock to become vitrified by human deeds; temperatures rise to slow in a natural fire and causes the rock to disintegrate before the stage of melting is reached. Yes, we can discuss eons on what we see, but the fact still stands.

[@youzerable]

It would be extremely difficult at the very least.

[@CS-zn6pp]

Oak would not be the predominant tree type in surroundings areas to most of these forts. The Scots pine would be the predominant tree in the west and north of Scotland at the time.

[@marcg1314]

I believe it was gorse that was used as well of which there has always been a plentiful supply. With it piled against the walls it could of taken years of burning and adding more gorse to reach the desired effect. Why they did it is a bigger mystery to me, does it strengthen the walls or did it just look minted. Nearest example of it for me is about 5 miles away at Dundonald and it's hard to find but small sections of well vitrified wall still exist there.

[@Jackdanalf]

I wonder if many trades were conducted in these places, such as iron working requiring lots of timber/ charcoal production etc perhaps a technique for fusing the stones was stumbled upon. The assumption is that these places were “forts” maybe so, or places to protect cattle from raiders/elite residents or meeting places .. enjoyed your film . We have lots of hill “forts” in Northumberland you should check out … I’m going to check them for vitrification!

[@julesdingle]

I mention and visited Yeavering Bell hill fort in a video cover Hadrian's Wall, and given the huge stone work walls and its similarity with NE Iberian Celtic hill forts revisit in the future- despite the stupidly steep climb

[@martybartfast1]

I wonder how many modern builds will last as long as the famed classics? But the regulations say they aren't up to Code. Great vid, thank you. m out

[@paulbriggs3072]

From zero vitrification on up to fused vitrification, the heating process does indeed fracture the stone, up to a point. From that point on when the fusing begins, then it fuses the heat damaged stone together. You can see that in some of your close-ups where cracked and damaged stone is partly fused together with its neighbor.

[@wazzarsa]

Hi. Thanks. I found the video very interesting. Would love to know more.

[@sillysausage2244]

Gorsewood would have been plentiful and burns as hot as charcoal, and hotter than oak. The ash is highly alkali, which I believe encourages vitrification.

[@julesdingle]

to sustain heat build up then the fuel needs mass, such as oak charcoal, gorse is a very fast fuel so great for the initial burn, and the heat needs sustaining over 2 days perhaps to melt a wall - gorse probably would sustain that, but very interesting you mention high alkali content- lime. Lime acts as flux reducing the temperature need down from 1,400 to 1,100 to cause fusing. I wondered if middens of shellfish shells could have been added, alternatively fine clay in the mix does a similar job, but gorse ash sounds interesting. Gorse would be great to start the fire in the wall, and at the end of that section there would be a big pile of ash that could go into the building the next sector interesting call

[@sillysausage2244]

@julesdingle Serious piles of old gorse, turves, heather and a stiff breeze - vitrification could have been repeatedly attempted in small sections. It clearly happened, so there must be a logical explanation. Perhaps the gorse was encouraged around hillforts as added defense. If it grew thick and was set alight one dry summer, could the peak of the hill be cooked for several days in combination with a peat/heath fire? I think the tree and shrub coverage could have been quite different 2,000 years ago, too.

[@bigbasil1908]

@@julesdingle Yes I think shells were probably used in the making of these vitrified walls.

[@julesdingle]

gorse burns fast as it has natural oils so ideal to get the fire going but physics requires a 24 hour cooking time within the wall and charcoal from oak scrub or even a lot of very dry oak is required for that sustained burn and physics to build up and retain heat requires a lot mass. in a 1 m3 wall section the amount of rock is about 1.5 tonnes of granite, but only requiring about 250 kg or so of charcoal to achieve smelting but the wall needs to be about 5m3 in mass to avoid heat loss the hills around these forts would have been hardwood scrub and woodland at the time, it is only in recent centuries these hardwood forests have been cleared and grazed to become moor

[@TheMadmacs]

@@julesdingle yeah i was just thinking after my sausage roll joke, i vaguely recall some vitrification happening with camp fires, maybe some fats were especially good in the process, like flux when you solder things, changes the game drastically

[@Warhawk76]

Its a very great privilege to get to hear about these structures from Jedi Master Qui-Gon Jinn!

[@AttackTheMoon]

Great video! Never heard of this before. What is the program you were using at 9:29 to illustrate your point?

[@donaldgrant9067]

Could this be done to the rock walls by putting sand in-between the rocks then fire put to them? Or a pulverized rock in-between the rocks and then Fire put to them? Just a question.

[@biggernumber1]

Gorse (Forze) is what was used, like in Greek fire

[@julesdingle]

gorse is certainly great for getting fires going given its intensity but for melting rock a long burn sustainable fire is required to slowly build up heat over 24 hours. gorse is intense because air can get to fuel but it takes up a lot of space and is burnt very quickly however the ash is lime rich, and lime is a flux that would reduce the melting point of rock so it may have had a role

[@ralphhathaway-coley5460]

Also I think people can sometimes forget that here in Scotland we do tend to have a lot of very high winds, essentially turning a fire into a Blast furnace. Personally I wonder why they are just using wood in the modern experiments, given that these vitrified forts are all in the Northern Europe, use the Forze to start the fire and get it up to temperature, but then use peat both as a fuel and as insulation, it is easily cut readily available and burns for a very long time if thick enough a layer is used it will burn for days, even weeks.

[@joelsmall4055]

yeah. no mystery here at all lol. +1 to gorse fire.

[@gudgengrebe]

Could the vitrified rocks be left over from volcanic activity and were collected by the locals for building? It seems like a lot of work to melt rocks into glass and why would they?

[@biggernumber1]

The Gorse will burn as long as you keep adding fresh gorse to the top of the pile. I saw an experiment (can't remember where) in which the gorse fire was kept smouldering for weeks and vitrification of the rock was observed. Maybe there was just so much gorse they needed rid of, in order to make that land useful, that they required places to do massive controlled burns safely, and that vitrification of the stone was merely incidental. Who knows.

[@dukeon]

Nice video. Love the eerie music…and appreciate the silence during the narration. Maybe less reverb on the mic?

[@julesdingle]

I didn't use my normal recording space, and the room was a little too echo .. also my voice was damaged in October after get covid in Germany and then ruining it for my Gold video Recording room is being refurbished so hopefully the next video will be corrected. constructive criticism always welcome!

[@philliphagan4760]

Interesting. Never realized they went to this level of effort with their walls.

[@pidginmac]

7:09 first example of anything ‘glassy’, with no examples of walls or other structures, just this random single fist-sized chunk some random person is claiming was ‘vitrified’. Offer some proof of your premise please.

[@colorbugoriginals4457]

maybe they found something they could apply to the rock that when exposed to a high heat source can burn much hotter than otherwise and turns the surface to glass right where it stands

[@ZacLowing]

Seeing how erosion might be an issue, eating away at the little hilltop room, vitrification might have been used as a foundational structure for the walls to be built upon.

[@thesquatchdoctor3356]

Both coal and peat are quite abundant in the isles, and both are good insulators. Piled on the sides of the rubble wall as supports, the loose rubble itself would act as the chimney for a fire, drawing the heat up and through the wall and vitrifying it as the supporting material burned away

[@julesdingle]

whilst coal is not found in the area- although some Jurassic coal at Helmsdale [where brochs are the fort design] someone else also mentioned peat as an insulator, and they would make for good form work that would also help melt facing pebbles good call

[@grahamtravers4522]

Given the high locations, and the prevailing weather, are lightning strikes a possibility ?

[@Paul-dorsetuk]

Interesting piece, thank you!

[@barryb1490]

Thank you so much for this, very informative!

[@leegould5306]

4:30 is that pipe work running through the stone?

[@RonTodd-gb1eo]

Would the virtification make the walls much stronger? Was the walls being broken down have been the main threat to the forts

[@helenamcginty4920]

If huge fires were apparently/ probably needed is this where the forests went? Plus were the mountains more forested then? There would not have been those wide vistas.

[@davidrowley-ic6dx]

I had never heard of these vitrified walls before … a total new one on me!! .. many thanks for the illumination. I have no awareness of having visited one of these vitrified sites … it seems (from the comments) they are actually quite widespread and I feel I must have rambled around the odd one or two over the years. When you first mentioned conglomerates, my immediate reaction was to assume this would be the most likely explanation … conglomerates are, after all, pretty widespread, notably in Scotland and people can easily interpret it as man made … “clear evidence” that early man had access to modern concrete!! However, the fused rock rubble is another matter. If I were to encounter it in the field, I think I would assume it was some form of long term mineralisation of the rubble as a consequence of extended wetting (Scotland being slightly notorious for rainfall). If, as is favoured, it is attributable to deliberate action by burning and the consequence of an alkaline reaction, then I would think any wood ash might support this. Indeed, what if construction was layered with peat ?? … Roman construction would utilise layered turf and timber to stabilise the structure against slumping. If peat were used, this could burn slow and hot … but would it burn hot enough?

[@julesdingle]

peat would certainly make for good retaining wall, if it were cut like it is for burning, it would retain heat and combustion would help create a more glassy finish for the facing pebbles. Ash as a flux or shells would have been known from iron bloom smelting practised 100s of years before and lowered the melting point. Tap O Noth & knockfarrel show the building material was small pebbles that are impossible to construct large dry stone walling - and would need form work I'm rather encouraged to try an experiment but scale is needed for mass, a 2m high by 2m long wall would need a lot of charcoal and granite ! good call on peat as both fuel and formwork

[@mrwatson-whitburnacademy6840]

The best vitrified fort I have ever come across is on Eilean nan Gobhar, an island in Loch Ailort. The sides of the fort are like glass and must have been an extraordinary sight high commanding practically the entire high ground of the island; 'There are two vitrified forts on Eilean nan Gobhar, a rocky cliff-girt islet. The larger (see NM67NE 2 for the other) occupies the summit of the isle and is sub-rectangular on plan, measuring c. 40.0m WNW - ESE by 22.0m transversely, within a heavily vitrified wall which survives on the S. to a maximum height of 2.5m' (Camore, Archeology Notes).

[@baldy3405]

Was this no in Arthur c Clark’s mysterious world ?

[@baldy3405]

It was 😂

[@RandomRangerRambles]

Is it known that these were vitrfied after the walls were built or is it possible that the stones were vitrified and then used for building?

[@julesdingle]

the rock was vitrified in place, this is evident that large sections of wall are fused together especially visible at Tap O Noth I was rather hoping the video was clear but acknowledge that video has its limitations

[@RandomRangerRambles]

@ thank you, just curious.

[@stendak]

This video seriously under delivers what the title suggests. Look into plasma vitrification on other ancient structures.

[@craigf2696]

Worldwide. Plasma glyphs, Gobi desert glass. On and on.

[@robblake6804]

Would it be impossible to build a fort, fill it with logs and burn it for weeks? Seems perfectly possible

[@sokar_rostau]

It seems that the most logical explanation would be that it was an intended mortaring process that turns a dry stone wall into a single pseudo-megalithic piece that cannot be easily undermined.

[@fibber2u]

One of the things a conqueror would need to do is destroy the fort if they did not intend to use it. So could the fires have been systematic after a complete victory and not just during siege or attack? Intentional but comprehensive unlike siege warfare which would have been concentrated on sections of the fort. The only reason for deliberate burning by the occupiers that I can think of, is actually to get rid of timber used in construction to prevent an enemy from doing so during an attack. But given the abundance of timber available I suspect these walls had a lot of timber in them and this aided systematic destruction when the fighting was over. I don't get the aesthetic thing at all, and can't see how burning (granite) stonewalls would give any structural benefit.

[@julesdingle]

I hope I presented the evidence that deliberate destructive burning is the mainstream opinion but also I'm speculating that possibly it was aesthetics given how difficult getting the conditions right is. Already a part 2 to this story is developing- I would like to recreate the experiment but its not cheap and very difficult to scale down given mass is essential for a long slow burn

[@fibber2u]

@@julesdingle The truth is we don't know. Your point of view is as valid as most others. It is also true that there is nothing too silly for it not be possible for it to become fashionable. Equally the-meaning-of-things and displays of status are not bound by what we may think is sensible. Somebody built the Great Pyramids.

[@freeforester1717]

Indeed, but not by a few thousand slaves as is often suggested. Too Many blocks far too heavy to have been built there and so precisely by modern era humans (in the past 3000 years. Remains a bit of an unexplained matter, much like the obvious water erosion of the sphinx body and its carved out lair. Brien Forster has made many good videos about this topic.

[@TheSpeartip]

Interested to find out more about Ord Hill

[@richardrose7382]

I had honestly hoped there would have evidence of a solar coronal mass ejection, that could have reached the surface of earth, with the intense heat needed to vitrify the walls, and incidentally killing any witnesses to the event, thus no written records. I can’t see the vitrification would make the walls more aesthetically appealing, and I even think the walls would more easily shatter if struck by a ball heaved by a catapult (although that may be technology of a later age) which could explain why intentionally firing the fort walls was not practiced in later constructions. But you seem to have explained the process well.

[@milnespetchristo1882]

Interesting video. Thank you. Shame about the voice-over quality of recording. Very distorted and sounded like you were too far from the mic?

[@julesdingle]

yes, as you will note from previous video my voice is cracking, I caught covid in Germany filming the gold video and my voice has not been the same since November- the narration was my 3rd take, but hopefully I will recover at some point And yes, I can always improve on pace and deliver- will take note

[@milnespetchristo1882]

@julesdingle thank you for the reply. And, I wish you a full recovery and the full return of your voice.

[@alistairmaclennan3791]

I was 10 years old and remember watching the Arthur C Clake program.At the time I thought maybe try burning the stone in peat .

[@freeforester1717]

Quite curious how every vitrified fort has the same aspect and date from the same time - how did they manage to 'coordinate' such a scheme without mobile phones?? 🤔 Diehold Foundation, series 4, Doug Vogt. Read too, The Cycle of Cosmic Catastrophes by Firestone, West and Warwick Smith, and also 'Cataclysm!' by Allen and Delair, for the evidence of the real explanation hiding in plain sight. 😊

[@julesdingle]

if they were a design feature then I rather suspect there were project manager/designers who were employed for their skill in the area, we know that brochs in the north share similar features so likely they were constructed by designers in a similar timeframe

[@ony5030]

Flood event of UV particles. Next event is very soon

[@isabelled4871]

There are some in France, too. So the knowledge was widespread.

[@GoldilocksZone-665]

It would have taken such a long time to build these forts. What, then, are the chances that the process would continue to deliberately setting fire to them to make them stronger? That's such a gamble. Also, has any testing been done on the vitrified walls to see whether the heat was more intense inside or outside the structures? It may have been a common form of siege warfare - to build fires against the external walls. That so many could have been accidentally set fire to, internally, seems a fairly remote possibility. Intense fires needed to vitrify stone. Or, maybe, they were set fire to either accidentally or deliberately INSIDE during warfare. Very hard, with Tap O'Noth especially, to haul enough flammable material up that hill to burn the enemy tribe out of their fort.

[@julesdingle]

the only practical attempt I came across was the 1980 one as featured, where they seem to have made numerous errors such as too little fuel, too larger rocks and no insulation - other experiments have been at a small experimental scale No search of papers on the subject presented any on the composition of walls- which obviously would be destructive to get a good cross section a part 2 to this is in the works and the next time I visit Tap O Noth I will look out for the things this episode has raised

[@davidprocter3578]

Like you I saw the Clarke feature on vitrified forts and the attempt to recreate a section. I was fascinated and seeing their failure started to wonder what they might have done to improve things. My first and most obvious thought was that they had not used anywhere near sufficient timber on or around the wall to develop the required heat. My next thought was to wonder how close were these forts to coal seams ? I did also wonder as to what real evidence was there that these walls had been timber laced through and through. was it conjecture??? What time of year were these forts fired ??? I imagine that it would have been summer day with a strong dry wind blowing at least a force five more likely force seven, one of those strong summer breezes that keep scuttling rain clouds past. Has anyone undertaken digging a trench out from the walls to see how far vitrification has spread , this might help indicate the size of the fire used. Was our climate slightly warmer and drier at the time of these structures construction ?? One has to wonder at the time scale of construction ? were these ramparts built over a number of years with cut/chopped firewood being mixed in with the stone and clear cut forests being stacked on top. Hardwoods like Oak are fairly slow burning at least in comparison to pine and ash Beech lime and elm all vary in burn time and temperature Lime being very slow and Elm giving the greatest heat, Did these builders know something about mixing these timbers to provide the required heat and burn time??My thoughts turned to charcoal burning and the use of turf to control burns. It seems unlikely that once built that the entire stack would be covered with turf probably because I strongly believe in the high winds theory , but it certainly would have been possible to cover certain parts in order to retain heat of course with that amount of heat repair to collapsing sections would have been impossible ?????? of course it may well be that peat turves were used instead of grass turf. This would have had the benefit of adding to the heat in that slow way peat has of burning, in depth it would provide both insulation and some extra heat something like a back burn.. Did small armies of people continue to throw timber onto the fire for some period of time ??? It is difficult to imagine just how many people it would require to keep a conflagration of that size going . Perhaps these walls were built in sections. I have often wondered were natural fluxes used to assist in the vitrification process limestone, sand, clay or salt , all these materials might have been added as broken stone mixed in with the local stone. Back in the day when the temps of brick kilns was not as controllable as modern gas fired kilns, often temps would get out of control and fuse bricks together with those slick blue black colours associated with this sort of accident , instead of wasting them they were often sold to builders who used them to great effect building garden walls or rockeries, so we know that sand and clay will fuse, limestone is used as a flux in the production of steal and salt to form glaze in the potteries. All this aside it is quite apparent that our ancestors knew a thing or two about building with fire that has been lost to us.

[@julesdingle]

you raise all the right points, the 1980 experiment didn't follow the same building techniques, there was no insulation and the amount of fuel inside the wall was too little and they burnt pine rather than oak and other hardwoods which would have covered the local hills Using physics [and I feel a part 2 to this story developing] then like the surviving walls, small pebble sized granite should be used for the facing layer, larger lumps for heat retention in the core and packed either with small lumps of oak or charcoal - about a 1/4 to 1/2 tonne of fuel for 1-2 tonnes of granite and incorporate wood ash, shells etc as a lime flux to reduce melting point. insulated with half a metre of dry turf, and possibly using wooden form work [or cut peat] to create a smooth facing surface I would love to repeat the experiment, but the minimum size given mass is key is a test wall 1 m high , 1 m wide and 2 m long would require 2 tonnes of granite pebbles and rocks, 1/2 tonne of oak or charcoal, and tonnes of turf not quite something I can do in the garden!

[@davidprocter3578]

@@julesdingle Of course you are right, not an experiment that would be easy to achieve a hill top to catch the breeze and not set fire to the native vegetation or any peat layers etc . Access for carting materials and labour for construction. Kiln dried oak generates tremendous heat known as white coal I wonder if our ancestors knew this ? I think it likely. the experiment might be best approached by building half a dozen such pyres varying their construction amounts of wood etc. And of course the resulting mess would need to be dealt with . And should the experiment succeed the land owner would need to be ok with the fused stone lumps remaining. You may have seen the same program I think it was time team though not sure fairly sure it was linked in with the stone henge series, an experiment on cremation one or two interesting parallels. I rather feel that the timber should be measured by volume rather than weight and might require as much as five to one. It occurs that these experiments might be conducted on a much smaller scale say a cubic foot of pebbles charcoal shells [crushed cockle shells easy to obtain.] using forced air to replicate wind, though not exact such an experiment might shed light for a larger trial.

[@aaronlarsen7447]

I dont think they needed vitrified walls, or went to all the trouble. In 1,700 years a forest fire or several caused it. Wild fires can melt steel, and cause trees to explode many yards away.

[@freeforester1717]

Would a wildfire of such intensity not leave more evidence though? Carbon deposits, surely? 🤔

[@tkp7162]

Curious to know what you think about the same type of thing occurring on the east coast of the USA. Geologically identical stone is found in Scotland and the US. There are plenty of oddly similar stone work constructions everywhere around New England.

[@OnTheRiver66]

It would be useful to measure the temperature required to fuse the stone in a particular fort, and compare that temperature to the temperature that an experimental fire develops using different fuels, such as wood, coal, charcoal.

[@1LivelyRogue]

I’m very new to this concept, but I gotta ask - why do we think they used a lot of wood? Wouldn’t fat be a better, more viable option? I’m thinking about the story of pigs set on fire to disrupt defensive structures in antiquity.