Vitrified forts — How and why?

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BrigantesNation B
BrigantesNation May 14, 2002 09:09:38
Replying to FourWinds

I thoughht I'd posted this last night - from UFO site!

"The rocks on which this fort are placed are metamorphic gneiss, covered with grass and ferns, and rise on three sides almost perpendicular for about 110 feet from the sea level. The smooth surface on the top is divided by a slight depression into two portions. On the largest, with precipitous sides to the sea, the chief portion of the fort is situated, and occupies the whole of the flat surface. It is of somewhat oval form. The circumference is about 200 feet, and the vitrified walls can be traced in its entire lengthÉ We dug under the vitrified mass, and there found what was extremely interesting, as throwing some light on the manner in which the fire was applied for the purpose of vitrification. The internal part of the upper or vitrified wall for about a foot or a foot-and-a-half was untouched by the fire, except that some of the flat stones were slightly agglutinated together, and that the stones, all feldspatic, were placed in layers one upon another.

It was evident, therefore, that a rude foundation of boulder stones was first formed upon the original rock, and then a thick layer of loose, mostly flat stones of feldspatic sand, and of a different kind from those found in the immediate neighborhood, were placed on this foundation, and then vitrified by heat applied externally. This foundation of loose stones is found also in the vitrified fort of Dun Mac Snuichan, on Loch Etive.

B BrigantesNation
BrigantesNation May 14, 2002 09:11:07
Replying to BrigantesNation

Hamilton describes another vitrified fort that is much larger, situated on the island at the entrance of Loch Ailort.

This island, locally termed Eilean na Goar, is the most eastern and is bounded on all sides by precipitous gneiss rocks; it is the abode and nesting place of numerous sea birds. The flat surface on the top is 120 feet from the sea level, and the remains of the vitrified fort are situated on this, oblong in form, with a continuous rampart of vitrified wall five feet thick, attached at the SW end to a large upright rock of gneiss. The space enclosed by this wall is 420 feet in circumference and 70 feet in width. The rampart is continuous and about five feet in thickness. At the eastern end is a great mass of wall in situ, vitrified on both sides. In the centre of the enclosed space is a deep depression in which are masses of the vitrified wall strewed about, evidently detached from their original site.

Hamilton naturally asks a few obvious questions about the forts. Were these structures built as a means of defence? Was the vitrification the result of design or accident? How was the vitrification produced?

In this vitrification process, huge blocks of stones have been fused with smaller rubble to form a hard, glassy mass. Explanations for the vitrification are few and far between, and none of them is universally accepted.

One early theory was that these forts are located on ancient volcanoes (or the remains of them) and that the people used molten stone ejected from eruptions to build their settlements.

This idea was replaced with the theory that the builders of the walls had designed the forts in such a way that the vitrification was purposeful in order to strengthen the walls. This theory postulated that fires had been lit and flammable material added to produce walls strong enough to resist the dampness of the local climate or the invading armies of the enemy. It is an interesting theory, but one that presents several problems. For starters, there is really no indication that such vitrification actually strengthens the walls of the fortress; rather, it seems to weaken them. In many cases, the walls of the forts seem to have collapsed because of the fires. Also, since the walls of many Scottish forts are only partially vitrified, this would hardly have proved an effective building method.

Julius Caesar described a type of wood and stone fortress, known as a murus gallicus, in his account of the Gallic Wars. This was interesting to those seeking solutions to the vitrified fort mystery because these forts were made of a stone wall filled with rubble, with wooden logs inside for stability. It seemed logical to suggest that perhaps the burning of such a wood-filled wall might create the phenomenon of vitrification.


Some researchers are sure that the builders of the forts caused the vitrification. Arthur C. Clarke quotes one team of chemists from the Natural History Museum in London who were studying the many forts:

Considering the high temperatures which have to be produced, and the fact that possibly sixty or so vitrified forts are to be seen in a limited geographical area of Scotland, we do not believe that this type of structure is the result of accidental fires. Careful planning and construction were needed.