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The Crannog- 
Shining Light On An Ancient Mystery

Crannogs are a peculiar type of residence built by our ancestors- the peoples of ancient Ireland. On this page, let us tell you everything we know about the subject. 

Before we start in earnest, come take a walk with us in the video below through one beautiful reconstructed example at Craggaunowen Outdoor Heritage Museum in County Clare, Ireland.

Much about this subject remains shrouded in mystery. There are conflicting archaeological findings, and dating them can be difficult to impossible.

 In this short article here we will give you the few facts that are certain. Let’s start with the basics.

Reconstructed model of a crannog at Craggaunowen heritage museum near Quinn in County Clare, Ireland.

What Is A Crannog?

The term refers to an artificial island built in a lake. These are some of the oldest dwelling places of humans in prehistoric Ireland.

They are found in Ireland, and to a lesser extent in Scotland, with a couple of isolated examples in Wales and Scandinavia, but it is safe to say that Ireland had the largest concentration of them in the world.

These sites were used as dwellings mostly, although archaeological findings have shown that some had other uses such as special places for metal work, fishing, or as hunting stations. Some  may have also been used for ritual deposition of weapons or sacred objects.

Thatched round houses at Craggaunowen heritage museum near Quinn in County Clare, Ireland.

What Does The Word Mean?

The word itself is Irish. It first shows up in documents dating from the 13th century. The first part of the word, ‘crann’, means tree and the second part, ‘og’, means young or miniature. There are two possible interpretations of what the name might mean. The notion of ‘young trees’ could refer to the appearance that a lot of these islands took after they were abandoned, as they started to be covered in young trees. Or, alternatively, the name could refer to one of the construction methods that were used to build these artificial islands in the distant past, which was by piling up tree trunks.

Friends of ours have a crannog on their land at Lough Gara, see it on the photo below for a good example of what they look like in the landscape. The lake was drained in the 1950ies and since then many artificial islands only become islands in winter time.

This is a real life unexcavated formmer island left from the times of ancient Ireland, located in Lough Gara, County Sligo, Ireland.

How Old Are They?

A lot of crannogs show evidence of multi period use right through the ages. They were built from Mesolithic times right through the Neolithic, Bronze and Iron ages, and continued to be used right into Medieval times. There are archaeological findings of materials from all these ages with most findings dating to the medieval period.

Why Did People In Ancient Ireland Build Islands On A Lake To Live On?

Good question. Archaeologists are left to guess work trying to answer it.

One theory goes that Ireland was densely wooded in the ancient past when these artificial islands started to be built, which might be one of the reasons people moved out onto the lakes because apart from upland areas, it was practically the only place from where you could see the sky.

Lakes could also have had profound religious significance for people of the past.  Another possible reason for choosing to live surrounded by water could be for defence purposes.

How Do You Make One?

Lough Gara in County Sligo has the highest known concentration of lake dwelling sites in Ireland. There are two main types that were discovered in Lough Gara.

The mound crannog was mostly made out of organic material such as big branches, lake mud (marl or blue clay), tree trunks, piled up in a mound to make an artificial lake island.

A cairn crannog was made by piling up stones.

Another, probably more rare method was to remove part of the lake shore in order to make some land, such as a small peninsula into an island.

A later type was constructed by driving tree trunks into the lake bed in an upright position and by building a wooden platform on top.

At a time when humans were using only simple tools made from bones, wood, antlers and stone, later bronze and iron, the work of constructing these artificial islands likely took a long time and involved many people such as a whole family or tribe.

Many of these islands were connected to dry land by causeways, either visible above the water surface or slightly submerged with the exact path only known to the inhabitants themselves. Others could only be reached by boat.

Many of these sites would have had a surrounding palisade of wooden stakes like the reconstructed crannog at Craggaunowen in County Clare on the photos on this page.

On the photo below see how the roof of the dwellings was constructed. Wooden beams that met in the centre were tied together using willow branches, and a thatch of reeds went on top.

Find Out More About Ancient Ireland

Find out about the dwellings of the ancient Celts.

Find out about the cattle herding culture of the ancient Celts.

Visit the outdoor heritage museum at Craggaunowen.

Read about neolithic Ireland, find out about the neolithic sites at Newgrange, Carrowkeel and Carrowmore.

The inside of a roof inside a reconstructed dwelling at Craggaunowen (which is an Irish heritage museum)near Quinn in County Clare, Ireland.

Other Facts

  • Archaeological digs have yielded valuable information and  numerous artefacts which have given us  insights into the lives of the occupants.
  • On Lough Gara, the average artificial island measures about 25m in diameter and reaches a height of 1.5m above the lake bed.
  • The number of artificial islands in a lake can vary. Some smaller lakes have one or two artificial islands where others could have anywhere from twenty to hundreds of sites.
  • Normally, these lake dwellings are located in small sheltered bays of lakes. They tend not to be built in open water.
  • Generally speaking the shape of these islands is round. Some were more elongated, such as the crannog at Moynagh lough in county Meath.
  • Some larger examples are known as ‘royal crannogs’ because they were assumed to have been the homes of high status members of a group.
  • For more in-depth information on the subject we highly recommend the wonderful book by the Swedish archaeologist Christina Fredengren, who spent five years surveying the artificial islands of Lough Gara.

We hope you enjoyed this article about ancient Ireland's most mysterious dwelling places.

If you did, why not tell your friends about this website so they, too may enjoy the content we provide! There are some easy-to-use social options at the bottom and top left! Thanks a million and warmest regards from Ireland from Colm and Susanna.

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