Melted rock forts of Scotland 

At first I thought the thumbnail was another Adam Savage one day build. In all seriousness thank you for this content. Great watch for sure!

Hello Simon. In AD 562, a comet passed over Britain from the North East to the South West, eventually passing over Bolivia. The country was devastated.... this is written in the ancient British texts. It also explains why the stones are vitrified towards the tops of the walls more than at the bottom. Hope this helps. Dr Charles John (Charlie)

Wish I had a teacher like you when I was at school, your an extremely interesting and well educated man.

A quick check on Google, the melting point of basalt ranges from 1175c to 1350c obviously depending on variation of chemical composition. That's well with in the range of any sufficiently sized charcoal fire.

You're overestimating the temp of molten basalt. It generally comes out of the volcanic vent at 1,200 to 1,400 C, and flows whatever distance, loosing heat as it goes. That's still pretty hot, but not as hot as molten iron (1538 C), and of course, iron was not very commonly actually melted, just heated to plasticity for beating, until fairly recently, though it could be done.

A wonderful video, thank you! We have such a distorted concept of time. If one thinks back to the medieval period, those that started work building a cathedral (the biggest buildings of the time), knew that they would never see it completed. We've almost universally lost this concept and I think it would do us a great deal of good to re-establish it.

My brother and I (12 years old) once built a tall furnace/chimney (5 ft) against a brick wall of our house. The aft side of the chimney/ furnace was the wall. We had a heap of kiln-dried pieces of white oak flooring as fuel. It burnt like hell! After 4 to six hours we let the fire go out. The next day we started dismantling our chimney/furnace. The chimney and wall bricks were fused together! The insides had turned to blue-grey-orange 'glass'! Our father did not appreciate our work. We thought it was fantastic!

I still think a Solar event could do the same. Maybe.

love it i think you cracked it.i think dragons might have helped on some of the other projects.

I think you have 2/3rds 9f the solution. In addition to charcoal and time, the missing ingredient is moving air which most forges use to increase the rate of combustion and increase temperature to the range where iron can be worked. Years ago, i found a description of how iron ore was processed into iron and steel. The process required selecting a hillside where the winds usually blew up hill. Then they dug out a deep trench going up the hill. Into the trench they loaded the iron ore and then filled the rest of the trench with firewood with a lot of smaller diameter branches, etc. Then, preferably when the wind was blowing uphill, they started a fire at the bottom and let the wind spread it up the trench and create a tremendously hot fire which smelted the ore into iron. Since this smelting was done in a carbon rich fire, the iron absorbed some carbon which turned it into steel which was then called Damascus steel and highly prized for its strength and hardness. Does any of this sound familiar? In the case of the vitrified stone forts, which i believe are always at the top of a hill and thus open to the Scottish winds. Now if an enormous pile of gourse brush was placed inside the ring of stones and set afire, it would create a lot of heat. If the wind was blowing fast enough, the heat generated would be much more intense and could probably vitrify the stones on the inside of the ring. If vitrification of stones was the intended purpose and they wanted to melt stones on the outside of the ring, an even larger pile of gourse brush would be needed as well as favorable winds. If the winds weren't favorable or even when they were, some purposeful focusing of the wind could be achieved via external structures using animal skins or woven materials, etc. Again, supplying that essential air supply to achieve much higher temperatures. This answers the "how?" question but not the "Why? question. It seems like a great deal of effort just to vitrify some stones, ostensibly to make stronger walls, so I suspect there may have been another more important objective.

First, this is truly fascinating and insightful. Second, am I the only one that thinks this professor looks strikingly like Adam Savage from MythBusters?

Brilliant film Simon , and credit to prof dad for solving a mystery 👍

The walls were built for fortification, but the walls also likely made a convenient tar kiln and charcoal manufacturing structure, and were likely repurposed between wars to make those. Charcoal was necessary for blacksmithing and the luxury of non-smoking fires in well to do households. But there are other products produced in this process. By reducing the air, destructive distillation occurs and turpentine and tar condense down into a liquid and pour from the bottom of the kiln. Before petroleum, this was how naval stores were made to preserve wood, ropes and make canvass. Fishing fleets had to have a tar fiber material as calking between boards and to fix hulls as well as the British merchant marine and navy which ran through a tremendous amount of this material. If the fortification was used as an industrial site to make charcoal and naval stores for decades, vitrification may have occurred. If all of that effort was made to build that structure, the inhabitants likely decided to repurpose it since they already had it.

Are vitrified fortifications inherently stronger than their stone equivalents? I ask only because, if not, there's no reason to think that these structures were formed intentionally, i.e., the vitrification could have been an effect of needing large, high-temperature fires, as in the iron age forges.

another great video thank you for sharing with us

Brilliant, so many people have come up with all many of crazy theories to answer this problem. And it was so simple all along.

I remember getting stuck on gorse as a kid in the 60's and it was bloody painful- I'm not surprised that it will burn for a long time given that it is an extremely dense wood- much like Boris Johnson-extremely dense. Unfortunately teflon now protects him...

Being interested in blacksmithing since I was young my first though was they used charcoal and forced air

Thanks Professor! I'm pulling for your Dad!

Sounds like your pap nailed it to me :-) not to mention it would be lovely and warm while its burning away, specially in winter, you get to reinforce the walls, keep warm and dont have to trek for fuel, it could be quite possible that the victrification of the rock was a by product of staying nice and warm in winter, i mean in summer in the old days you still needed a jumper for scotland :-) great share professor

The same occurs at the South American megalithic sites. Signs of stone vitrification and liquification running down the face of these brilliantly constructed stone walls. The way the stones fit together such that a penknife can't be forced between, may have been achieved through softening of the rock. If I remember rightly it was at Sacsuayhuman that featured parts of the wall turning to glass and running down the wall-face. Probably Cusco and other locations as well. Worth checking out

maybe they used a rocket stove idea, if so there might be an air intake channel from outside the fort to the inside base of the gorse fire, that would increase heat with complete combustion of charcol

Great vid, I remember the Arthur C Clarke episode on the Hill forts, I loved that show when I was a kid. At times over the years I’ve wondered how they might have done it, thanks for giving us the answer Prof.

Professor Simon, you certainly have a unique and wonderful way of blending the learning experience, with old-school story-telling, mystery, wonder... and awe. Thank You So Very Much for sharing your knowledge, your insights, suspicions, and occasional hints of uncertainty! All the while, encouraging us to put on our thinking caps, turn on our critical thinking, and for treating & including us to some fascinating discussions in the search for the truth.

That's GREAT!! It's also exactly what I've always maintained. I have never thought of "the ancients" as ignorant, despite the "caveman" allusion when I was in school. WE wouldn't be here if our ancestors weren't resourceful. I can also tell you those stone spheres, found in the NE of Scotland were used to knit gloves, socks and whatever else was needed. They were important items, and prob. handed down over the years. Same goes for all the Roman Stone Spheres. I recently saw a megalithic site that people were so baffled by. There was a "wooden box" filled with rubble and left hanging up high in the air. While there was another "box" empty and on the ground. They just could not figure out how or why they were like that. All I could do was scream at the screen..."HAVE YOU NOT HEARD OF SIMPLE PHYSICS?" LEVERAGE PEOPLE. Simple pulley system can lift just about anything. That one man built a scaled down Great Pyramid all by himself, by merely using one stone to lift the other. A pulley and weight system. Yes you can cut the pyramid stones and place them all by yourself. Don't get me started on the "nubs" everyone is so fascinated by. I feel like the fringe archaeology channels on YT want it to be aliens so bad, that when the obvious is staring them in the face, they simply say, ya but.......how did they move them, why, and so on and on. They can't accept that man wasn't stupid.

Nice :) . Being local Pehta have always been fascinated by our sequence of vitrified forts and yes you've deffo brought a new idea to bear. Like it a lot Would like you to also note the other technology you mention, that of forced air. The forts tend to be what ate known as timber laced whereby the dry stone walls were threaded through with solid oak beams every 6 feet horizontally and vertically and that when a fire was set yhese beams would have burnt through bringing the heag of the fire deep into the structure and opening forcing flues throughout the structure which combined with the hot charcoal effects of the gorse may well have made this a reasonably 'easy' and rel8ably repl8cable technique . Tidy Ta gain :)

Can I just say I love you speaking style in these videos it's very calming and relaxing but keeps me intrigued and focused as well. Just subscribed, liked and now commented. Keep up the good work!

More science please . Interesting stuff .

Burntisland is in Scotland. Also, sedimentary rock when heated makes lime. Igneous rock makes a kind of glass like substance, but not glass per ce.

Interesting . You have ommitted two factors here. Firstly the use of lime as a building material throughout the interior of stone structures and secondly the massive quantity of timber used in their intitial construction . This combination ,at the time of the buildings deliberate destruction by fire ,would raise the temperature to 1320+C assisted by the fluxing effect of lime to melt the rock's surface . It is my view that all the vitrification came about as a result of the demise of the structures by burning not as part of their construction .. This is almost confirmed as not all demonstrate any vitrification and all those that do have the majority displayed on the interior only . The gorse story may be a 'red herring' and not truly applicable here. In addition there is no structural or practical reason to vitrify the structure. . Lime , in its various forms , is an easy to use sealent and binder with horsehair or reed fibres to add rigidity in lining walls and ceilings and has been used for millenia. Lime is also used in certain types of glass making as a fluxing agent . . Thanks

Being scottish I do think youve got one of thee best accents on RU-vid ;)

What a coincidence ... we just visited today Kildonan Dun. Thank you for the insights about these beautiful ruins left by our ancestors. We moved recently to Torrisdale, so we do want to learn more about this beautiful part of Scotland. Thank you.

cheers Prof, i remember climbing an enourmous hill (covered in gorse) a few years ago to see a vitrified fort, thanks for solving the mystery :)

Hot topic - hot enough to melt rock. Those oddly shaped, yet impossibly snug fitting stone walls in Machu Picchu - I always thought were liquid stone (cement) poured into canvas bags and left to dry. Then the canvas was stripped away. I still haven't worked out the vitrification process, but I'm working on it. So far I've got a long list of what WON'T melt rock - ketchup, dirty socks ground to a paste, a car engine left to run it's gas tank empty with exhaust pipe shoved into the rock pile. And many more. Still solid rocks, though.

There was only 1 melted rock fort outside of Scotland and it was in my hometown of Huddersfield , im looking at the hill on which it once stood out of my kitchen window right now.. My question is why bother melting the rock instead of just leaving it or pulling it down ? Seems like alot of work for no reward?

Love this channel.really enjoying the charismatic story telling.thank you .💙uk

Professor Simon super fascinating history of how the ancients melt rock!

Brilliant, thanks for sharing👍

You're a real scientist, so rare to hear a passionate seeker of truth these days

Very well put! Excellent presentation! Thank you

As a Hawaii resident this is relevant to my interests. Vitrifying a rock wall would be much more interesting than cementing it.

Professor Simon. Amazing video. Just think of time and labor involved in melting rock. Kenneth.

Similar examples of this type of ancient technology (melted and molded stone, even obsidian) can be found in several Indian temples that go back several thousands of years.

Great topic, and Adam’s best costume yet!

Why would you want to vitrify the forts, what was the purpose?

So, Professor, I have a observation and a question. Viewing the video segments where the vitrified rocks are shown, I was examining, as best I could, the edges of the vitrified rock. The edges appear to be made up of smaller rock set between the 'larger stones'. When the segments of the Wall were fired, wouldn't the smaller stones be the first to achieve the needed temperature to melt? And as such temperature were reached to melt the smaller rock, the edges of the smaller rock would begin to melt or solidify to the adjacent larger stone. As the temperature of smaller rock increased, so would the larger rock's temperature at the edges also rise to the melting point. And then the material would 'flow' together and bond. It seems to me that the bonding of the two materials would have achieved the desired purpose to make the rock a whole singular combined stone, which would be stronger as a whole single section as opposed to two sections made of like stones, even if the smaller stones were vitrified and the adjacent smaller rock was not 'melted' into the larger rock. Just a thought. Good food for thought.

Awesome video!! So much history on your side of the world. Generations ago my family came from Scotland, I would love to take my wife and kids to visit one day!! Keep making the great videos Sir, much appreciated!!!

I am convinced this man is a wizard. Subscribed.

Lived in Inverness for a while. There was a vitrified fort on top of the hill near my father's house. Always had me puzzled how it was done

I was told by older relatives as a child it was Dragons attacking the Fort. I like that version to this day

An experiment MUST be made!

This popped up recommended by RU-vid tonight. I live in Torrisdale and it just so happens that I visited the fort that your mother and father cleared this afternoon. How spooky is that! Great video by the way...really enjoyed it.

The BBC tried to do this in the 70's I think on a 12ft wall, they actually ran out of wood after 3 days and managed to find a tiny piece. The alternative is the theory of the meteorite in AD 562 ,which makes more sense than this.

Hello Sir, So I discovered your existence on RU-vid about 12 minutes ago and I'm happy I did. This particular video is my first time watching you and I must say YOU, Professor Simon Holland, are the first and only person to give a reasonable interpretation of past happenings. FINALLY SOMEONE ELSE WHO HAS A BRAIN THAT THEY ACTUALLY USE!!! THANK YOU, ABerCul

I enjoy your videos! Subbed!

Beautiful and interesting video. You are a great storyteller!

There are verified structures all over the world, on every continent, especially in the deserts, possibly something else happened, and it happened everywhere. Vitrified, not verified, silly text.

Sounds like a winner of a video and idea. It is slowly coming out that around the time of the Adena and Hopewell cultures in N America that an early culture in Appalachia was smelting iron impliments. These are not what is known as native americans or Indians but an entirely different race. Possibly these races came from Scottland or Wales but actually no one knows where they came from. The Adena most agree built the Serpent mound and other mounds throughout the Midwest. They also built the great clay pyramids which was the center of a city of about 10,000 people across the Mississippi River, the east bank of the river, from St Louis. They were in many respects more advanced than the Native American cultures than replaced them many years later. They existed during the time of the Mastadons in N America, an ancient wooly mamouth type creature and have been exhumed hunting them in the what was known as the Great Black Swamp of Northwestern Ohio that existed during the War of 1812 and where the far most western edges of where this war was fought. The manufacture of iron compliments is what is setting my minds imagination into action and the fact that people from Whales and Scotland did migrate into N America long before Christopher Columbus discovered it along with races from Norway and Sweden. This is all pre-last-ice age history. Most of these races never recorded the discovery of a new massive continent as most considered N America as a western extension of Europe. So throw you a mystery, who were these early Pre-Native American settlers of N America? The earliest settlements ran from Labridor in Canada to roughly Providence, Rode Island. The extended clear out to St Louis and Minneapoli-St Paul. They where far more advanced than the Indians and their DNA tests suggests that racially they were not the same race.

You have some great videos!

Congratulations on this being one of your most viewed videos Professor!

I don't know the archeology/history of these vitrified 'forts'. But, rather than a fort, could they have originally been (or at least mostly) places of pilgrimage/festivals/ritual. Where they created large fires in these stone circles (using the wood mentioned). And, over generations of burning, these walls vitrified. Perhaps, with other times in their history, when they were used for habitation. I only say that as, the benefit of verified stone (in these walls) for the true 'fort' seems overkill (unless, created as a byproduct of some other ritual). If I actually wanted vitrified walls, using the ideas you mention: I would pile the gorse wood (or, charcoal, made from gorse - maybe better for the task) over and around the whole stone wall structure. Then, using earth and water, create a clay. Using that to enclose the wood/charcoal (and wall) in the earth/clay. But, leave the ends of this 'clay tunnel' open to the elements (and perhaps, even create openings around the clay structure at key points). Given wind power on the coasts of Scotland, that might allow (at the right times of year) for a sort of natural 'bellows' effect through the clay structure. Basically, your building a furnace ..with the wall at its centre :) Peace.

This is so interesting! I’m thinking that there are maybe a couple of factors at work: 1) The thick pile of gorse and layers of smoldering charcoal and ash insulate the deepest part of the fire. I don’t know if there’d be enough oxygen getting through the layers of actively burning material above the lowest levels to support combustion there, but if any did at all, the heat generated from even minimal combustion would have trouble escaping. So temperatures could get much higher than in a normal bed of coals on a hearth. 2) Over short periods of time, the rocks would absorb and conduct away heat energy, but once they were heated to a significant distance/depth, the surfaces in contact with the coals could get very hot indeed. Rock isn’t a great thermal conductor, so given enough heat input over a long enough period of time, it would make sense that the surface facing the fire could get extremely hot. I think the main revelation here is that we tend to think of things as having various characteristic temperatures when burning, but we’re only seeing them when they’re in open air and the thermal energy generated is being radiated/conducted/convected away. In reality, the temperature we see is a function of how much thermal energy is being created vs how much is being taken away through various processes. Oxidizing a given amount of charcoal produces “x” amount of heat, but if you don’t let that heat escape, and then oxidize another amount of charcoal on top of it, the temperature is going to get much higher than as it was just burning normally on a hearth or in a furnace. I don’t know, a friend of mine once said that I could come up with a random theory to support any set of data in 10 minutes or less - and then just as quickly think of a totally different theory if it turned out the data was wrong - so my theories may not have a lot of merit. Still, this is a enormously interesting story, and shows that our “modern” thinking can often prove to be very limited :-)

That was a fun AND interesting video! Thanks!

The best explanation I've heard for vitrified stone forts in Scotland and I appreciate your point about time: As an engineer my decisions are not based on the economics of something not over it's lifetime or even a five year net present value but project economics are based on year quarterly rate of returns and therefor it's pure madness. I've seen melted staircases in Egypt and Peru that would seem to need to have a different mechanism however.

After watching half of this video, I discovered that I still knew nothing about how the ancients melted rock. Skip to the last minute or so. He just says it there. Or basically... ...they piled gorsewood charcoal inside the structures and made a fire burn for weeks on end which melted the rocks on the inside.

hi prof simon! it's interesting how they did it. but i wonder how you transported the molten stone....thanks for the great video. have a nice day!

Great video!! I subscribed!

Another great one professor

It's interesting how ever serious historians forget (a) how many people were actually in the countryside prior to the industrial revolution and the birth of the modern city, Thereby providing a vast amount of personpower. I say personpower because women and kids would have joined in. All it took was someone with authority to manage the people. Also (b) that a lot of things can be accomplished given a large amount of time. We think of things in terms of mechanical tools and machinery. But for instance the canals of England especially in the early stages were built using an almost infinite number of navvies and.... time. Yes, things took less time as machinery became involved and that's the sort of timescales that modern people assume things took back in antiquity. But turning a Basalt tower into basically a huge blast forge and leaving it lit for a year isn't beyond the technology of the time. Lots of fuel and an opening in the base to create a draught for the fire. Plus there was more wood and trees in Scotland back then. A lot more. Plenty of raw material to make charcoal if required.

My guess: Dragons and Druids (wizards) are the two ingredients you need to melt a Scottish stone castle! Which were more common back then, then they are now, after English Knights arrived 'on the scene'. Now I'll watch the video!

I'm a union boilermaker. I have spent many years working in and around and repairing steel mills. Maybe these were not forts at all but open pitfoundries. Put all your iron ore inside pile up the gors light it on fire and keep feeding the fire for some time. Maybe they even made hollow balls of clay to put iron inside of to keep it from being exposed to the air while melting. 🤔 Intriguing. What if a lot of these forts actually started off as foundries and everybody else got it wrong. Just to later be used as forts after they were abandoned as foundries

Thankyou for you knowledge, I appreciate it coming from your family history. Its a source of true events.

Always nice to learn something new every day.Thanks Prof. (Although there is only one T in Scots and i have no skin in the game having supposedly Pictish DNA).

I LOVE how much debate this has sparked! One of your more successful videos professor in that everyone is engaging!

Very interesting. Thank you Professor Simon.

Love you channel , ❣️ I always learn so much.

Of course anything can be done, If one knows how to do it ! My late dad used to say "sometimes the impossible just takes a bit longer" haha

I love your videos Simon, nice to hear an intelligent POV. Cheers from Calgary AB.

Holy Molly! The Scottish Adam Savage from 20 years in the future!

Nice story. Very interesting video 😉

Thanks professor I love this kind of material. Thanks

Dear Simon great to see you again....gorse does indeed burn hotter than a lot of woods to , but it also smells unmistakably like coconut not vanilla...keep up the fab videos

In the 500's, according to what little records we have, there was a meteor that flew over the UK and essentially depopulated the land. I would assume it was this incredibly hot meteor that perhaps melted stone forts etc.

Very well put. iron age people were not under pressure to leap. They used what they had- including patience. Which is why my theory of how Stonehenge was built over generations during the farming off-seasons of Winter by 1., dragging sledges bearing the stones on snow and ice, and 2., cracking rocks in mining with fires and freezing ( as Hadrian did whilst crossing the mountains to get to Rome), makes perfect sense. 3/. The blue stones represent dead people (blue) and the positions of the stones in situ make for amplified vocal harmonic resonance of healing frequencies in ritual healing ceremonies.

This was brilliant!

Intriguing channel Sir. I thoroughly enjoyed the video. Scottland is truly a breath taking land😎

Both my daughters now live not far from your own upbringing place, eldest is in Dunoon and youngest is across the water in Clydebank, my own forebears come from Perth, Edinburgh and Aberdeenshire, one thing our family did was found village and town schools across northern Scotland as well as that school in Edinburgh, teaching and educating is a family business so to speak :D

Very well done!

I was sure this was Adam Savage from myth busters. Great vid.

Wow, clicked for the content and read the comments first. I tip my hat.

Hey thank you clears up a question or two. The point is they always used what was at hand if they could. Great video

It's everywhere in out world. Old castles and forts literally singed into mountains and volcanos

Fascinating video 👍

A very interesting video, really makes you ponder the possibilities for the true purpose of what appears to be controlled burns. Good suggestions made in some of the comments also. Looking at maps of early medieval Scotland it does seem that there may be slightly more of these vitrified forts within areas that were classed as medium or poor quality land. Perhaps one of the intended outputs was utilising the wood ash as fertiliser.

So why would they even bother melting it or to what purpose? Thank you Prof 😉 Edit: interesting comment below about Why.

Great film

💯🔥🙏🏽 Enjoyed learning about ‘long time’ & how many ‘old time’ structures

Great video

Very fascinating subject ,for a side note we here on the left coast of Canada call gorse Scotch broom and I recently learned that the wood makes beatiful spoons and the like. Loved this video Simon and would love to visit your neck of the woods some day

If you stacked the gorse, or gorse charcoal thickly about and on top of the walls, inside and out, then stacking thick mud bricks all over, leaving air openings and chimney holes, basically building a kiln around the structure, I can see that working faster than simply stacking gorse and setting it alight.