Vitrified Stone Walls

I like the idea that wooden structures or buildings erected adjacent to the no-longer-used fort walls burned down. By pure coincidence, the high winds of Scotland turned a bonfire into a blast furnace that day.

Remember that vitrifying a fort wall weakens the wall, so this is not an improvement in the defensive value of a fort. To my knowledge, no breached walls were found to be vitrified for breaching thus this was unlikely a technique for attacking a fort.

Another idea I like is the old fort wall became the permanent wall for smelting ore. The other walls of the furnace were dismantled to reach the newly smelted metal.

Forensic archaeology dating techniques might be able to identify when walls were built and when they became vitrified. Knowing these approximate dates could help determine if the intent was improving the fortification or reusing what was no longer useful or even if just an accident occurred.

There are a few techniques that identify when glass gets formed but I suspect most of them require the glass to be relatively thick. A thin layer of vitrification may not be useful for dating.

Ther is an assumption that only buildings nearby would have burnt, but at that time the old Caledonian forest surrounding the hill would have contained far more trees than the population would require.

Put that hill fort in the midst of a raging forest fire and the heat would be far higher than a pile of sticks could achieve.

Also, the Roman army was around at that time, so foul play from them cannot be discounted. Arrive up wind and set fire to the trees so they don’t get ambushed (again).

Here is an analysis. The author's conclusion is that the temperatures required were well within the capabilities of people who were smelting iron, but that the reason for the vitrification is still a mystery.

Dunning, B. "The Mystery of the Vitrified Forts." Skeptoid Podcast. Skeptoid Media, 4 Sep 2012. Web. 29 Feb 2024. <https://skeptoid.com/episodes/4326>

My theory is that the guards that stood atop the walls never left their post to urinate, and over the years the urine added salt to the walls allowing for low temperature vitrification during structure fires over the years...

Right on, good answer!

Someone made Emilia Clarke very angry,or she could have just walked by....

Way back in the late 1800s there was a brick smelter used to smelt gold from the quartz up around an are known as Black Snake. Now this smelter did not have any external forced air but relied on being built on a promontory with deep ravines on each side. The winds rushing up these ravines were directed to the furnace, made of brick with a tall chimney for draft. The bricks were vitrified from the heat.

Also I have noticed that clay crucibles I use for Aluminum smelting running purely of induced draft do get hot enough to vitrify around the top edge so the thought that the winds form a plausible explanation for the vitrification. As a side note I make my own charcoal and it does not take a great deal of that fuel to get very high temperatures, no more than a few pieces of hardwood turned to charcoal.