Among Ireland's most fascinating and mysterious archaeological sites are man-made circular or oval islands in lakes. Some crannogs - the word comes from the Irish, meaning a small island built with young trees - are stone cairns and earthen mounds around lake shores. Whatever their form, they share the same abandoned appearance: once busy dwellings and settlements, they now seem as haunted as any empty house, inhabited by the ghosts of an ancient people.
Many a modern fisherman has made use of a long-deserted ancient crannog. Although often in desolate and remote locations, they have proved extremely useful to archaeologists because their waterlogged condition acts as a unique aid to preservation. Rich clues to our past, and particularly to social and domestic habits, are contained in the wealth of ancient plant remains, seeds and animal bone. It is possible not only to discover what the ancients ate, but also to understand their building techniques and farming practices.
Archaeologist Aidan O'Sullivan, author of Crannogs: Lake Dwellings of Early Ire- land, has a particular interest in landscape and settlement in ancient Ireland and is a programme director with the Discovery programme. His comprehensive guide to these mysterious lake dwellings is a characteristically informative and well-illustrated addition to the Irish Treasures series, published by Country House, some editions in association with the National Museum of Ireland.
Edited by Dr Michael Ryan, the series to date, with 24 publications - many of them superb essays in which every word carries value - includes Roger Stalley on Irish Round Towers, John Bradley on Walled Towns In Ireland, Conleth Manning on Early Irish Monasteries and Sean O Nuallain on Stone Circles In Ireland. My only criticism is that the touristy series title, Irish Treasures, demeans what are serious, scholarly and accessible essays.
To date, there are about 1,200 known crannogs on the island of Ireland, sometimes built in shallow water, sometimes up to hundreds of metres out from the lake shore. O'Sullivan suggests there may well be further hundreds, "if not thousands", yet to be recorded in Ireland's lakeland regions, still concealed because they remain submerged by water, hidden under marshy vegetation or buried in waterlogged peats and clays. The highest density of crannogs is throughout the lakeland region of the north-west and across the drumlin belt. They are also to be found in the south midlands. Crannog builders tended to concentrate on smaller lakes, as the more exposed shores of large lakes such as Lough Erne and Lough Derg would have been subject to stormier conditions.
It is believed crannogs were first built in Scotland during the third and fifth centuries, and in Ireland from about the late sixth and early seventh centuries. While much remains to be learned about crannogs, 19th-century antiquarians, such as William Wilde, William Gregory Wood-Martin and William Wakeman, were busy in the field. Between 1839 and 1848, Wilde recorded discoveries made by labourers on the crannog of Lagore, in Co Meath.
Archaeological evidence suggests several Irish crannogs may have been inhabited over long periods of settlement. Moynagh Lough in Co Meath, for example, excavated by John Bradley, appears to have been inhabited for at least 200 years, while Lagore was populated from the sixth to possibly the 11th century. Initially, such sites may have been individual homesteads, but by the ninth and 10th centuries, they appear to have been used on a larger scale, even serving as royal residences.
Certainly, there are indications that Moynagh Lough, a vast site, was a royal dwelling that was also used for feasts and assemblies. While lake-dwellers had to contend with the weather and were constantly maintaining the structures - largely constructed of timber, brushwood and peat - the greatest enemy to the crannog was the arrival of English forces during the Tudor re-conquest of Ireland.
Among the many insights O'Sullivan offers is on the use of crannogs as centres of craft and industry as well as farming. To date, about eight or nine crannog sites have been well-excavated.
Modern crannog reconstructions may be visited at the National Heritage Park, Ferrycarrig, Co Wexford; at Craggaunowen, Kilmurray, Sixmilebridge, Co Clare; and at the Ulster History Park, Omagh, Co Tyrone. At present, visits to all heritage sites continue to be subject to footand-mouth restrictions.
Crannogs: Lake Dwellings of Early Ireland by Aidan O'Sullivan (Country House, £5.99)