Vitrified fort facts for kids

Vitrified forts are ancient stone forts. Their walls have been heated so much that the stones partly melted and turned into a glassy substance. For a long time, people thought these special forts were only found in Scotland. But now, we know they exist in other parts of western and northern Europe too.

These forts are usually built on top of hills. This made them easy to defend against enemies. The shape of the fort often followed the natural shape of the hilltop. The walls are different sizes. Some are over 12 feet (3.7 m) (3.6 meters) tall. They are also very wide, looking like big earth banks. If a part of the fort was weak, builders added double or even triple walls. Sometimes, huge banks of unheated stones were built far away from the main vitrified fort. These extra walls helped protect the fort.

These forts don't use lime or cement to hold the stones together. Instead, the rocks themselves were melted together by intense heat. This melting is not always the same. In some forts, or even in different parts of the same wall, the stones are only partly melted. They might just be slightly burned. In other places, the edges of the stones are melted together. This makes them stick firmly. Sometimes, pieces of rock are covered in a shiny, glass-like coating. This coating binds them into one solid piece. Very rarely, an entire wall is one solid mass of glassy material.

Why Were Forts Vitrified?

It is still a mystery why or how these walls were heated. Some old thinkers believed it was done to make the walls stronger. However, heating the stone actually makes the structure weaker. It's also unlikely that battle damage caused the melting. Experts believe the walls were heated by carefully controlled fires. These fires had to be very hot to melt the stone.

Most archaeologists now think that the forts were vitrified on purpose. This might have happened after an enemy captured the fort. Or, the people living there might have done it themselves. They might have done it when they left the fort for good. This act could have been a ritual, like closing down the fort. The process of vitrification happened at different times. It is found in forts from both the Iron Age and the Early Medieval period in Scotland.

Where Can You Find Vitrified Forts?

A geologist named John Williams first wrote about these forts in 1777. Since then, over 70 vitrified forts have been found in Scotland. Some of the most famous ones are:

• Dun Mac Sniachan (or Dun Mac Uisneachan) in Argyll. This is the largest fort, measuring 245 meters by 50 meters.
• Benderloch, north of Oban.
• Craig Phadraig, near Inverness.
• Ord Hill, North Kessock, near Inverness.
• Dun Deardail (or Dundbhairdghall) in Glen Nevis.
• Knock Farril (or Knockfarrel), near Strathpeffer.
• Dun Creich, in Sutherland.
• Finavon (or Finhaven), near Aberlemno.
• Barryhill, in Perthshire.
• Laws, near Dundee.
• Dunagoil and Burnt Islands, in Buteshire.
• Mote of Mark, near Rockcliffe.
• Trusty's Hill, Anwoth, near Gatehouse of Fleet.
• Tap o' Noth, Aberdeenshire.
• Dunnideer Castle, Aberdeenshire.
• Cowdenknowes, in Berwickshire.

For a long time, people thought these forts were only in Scotland. But they have also been found in other places. These include the Isle of Man, County Londonderry, and County Cavan in Ireland. They are also in parts of Germany, such as Upper Lusatia and Saxony. You can find them near the Rhine River. Some are in Brandenburg, Hungary, and France. Examples in France include Sainte-Suzanne and Puy de Gaudy. They are also rarely found in northern England. Broborg is a vitrified hill-fort in Uppland, Sweden.

Vitrified Forts in Media

Arthur C. Clarke's Mysterious World

The TV show Arthur C. Clarke's Mysterious World featured vitrified forts. In a 1980 episode, archaeologist Ian Ralston looked into the mystery. He examined the fort called Tap o' Noth. He tried to recreate how the vitrification might have happened. He piled stones and built a huge bonfire. This was similar to experiments done in the 1930s. His experiment produced only a few partly melted stones. It did not fully explain how large forts could have been made this way.

Images for kids

• 

  Part of the vitrified wall at Sainte-Suzanne (Mayenne)

• 

  Fragment of vitrified wall at Sainte-Suzanne (Mayenne)

See also

In Spanish: Fuerte vitrificado para niños