The magnificent Céide Fields in County Mayo
The Céide Fields, as understood today, is a network of parallel stone enclosures with a number of those walls running up to two kilometers in length. The site has been mapped up to ten square kilometers or four square miles but it is clear that the site is much more expansive than these numbers suggest. Although there is one known domestic structure (Seamus' oval enclosure) found, there must be others.
The sheer scale of the site is an indication of the size of the population and the degree of organization that it would have taken to construct such fields. The area, at the time of the stone enclosures' construction, was a dense primeval forest filled with animals that today can only be found in Ireland's museums, including wolves, brown bears and boars. To clear this landscape for agriculture, let alone move the over a quarter of a million stones used for the enclosures, would have taken a great deal of cooperation from a sizable community. This society would also have to have had a source of food production independent of these new fields and independent of the population working on them.
No evidence has yet been found of any fortifications at the Céide Fields. This has prompted many into believing that this agrarian society lived peacefully without thought or threat of war. Although this is a tempting and agreeable hypothesis, it is argued from a position of lack of evidence rather than proof positive.
The Céide Fields' society did not live in isolation. We know that the population participated in trade and therefore certainly had contact with various other peoples, as evidenced from a number of flint and Porcellanite (used for stone axes) finds from County Antrim in the north. It is certainly possible that their interaction with neighboring groups was completely peaceful, but it is unlikely. Just because defensive structures, such as protective walls (which would be larger and thicker than the farming walls) and tower foundations, have not been uncovered is not reason enough to presume that they do not exist. The Céide Fields is such an expansive site that these structures could lie undiscovered deep beneath the bog miles away.
What first enabled the bog to grow in this region is debatable. Some believe that it was a change in climate or high amount of rainfall that eroded the soil's nutrients enabling the growth of bog-forming plants which require minimum sustenance and thrive in saturated conditions. Others feel it was the human impact on the forested environment that permitted the necessary conditions for the bog. It is likely that a combination of both climate and human intervention caused the optimal environment for the blanket bog to develop.
Although the origins of the bog are debated, it was certainly because of the bog that the Céide Fields became unsustainable. The fertility of the soil deteriorated, forcing the population to leave. It was a relatively slow decline, possibly occurring over centuries.
The lands around Ballycastle and to the east, along Killala Bay, were not affected by the rising bog, and it is likely that many of the Céide Fields' inhabitants relocated not far from the area.