Lough Neagh, or Loch nEathach as it is known in Gaelic, a large freshwater lake that lies in the heart of Northern Ireland. At an impressive 20 miles long by nine miles wide, 396 square kilometers, it is the largest lake in the British Isles. Its magnificent size, among other attributes, prompted many myths and legends on its origin. I found tales on the creation of this lake in Ireland’s Own, a fascinating journal about Irish life and culture that was founded in 1902.
I came across many legends that attempt to explain the origin of the enormous Lough Neagh. Some of them involve a magical well that, when left uncapped by an aloof townsman, overflowed and flooded an ancient city, a common theme in myths regarding the origin of Irish lakes. Depending on which story you’re reading, all of the inhabitants were either tragically drowned by the flood or still exist along with the city in all of its glory, submerged under the many feet of water.
An anonymous poem I came across in a 1922 copy of Ireland’s Own describes the underwater city that is rumored to be visible on a calm, clear evening.
On Lough Neagh’s banks, as the fisherman strays,
When the cool, calm eve’s declining,
He sees the round-towers of former days
In the wave beneath him shining.
As another tale goes, Finn McCool, the legendary Irish hunter and warrior, known as Fionn mac Cumhaill in Irish, after encountering a Scottish giant, scooped up a handful of earth and threw it at his retreating foe. The depression this handful left in the ground was filled by rainwaters and over time became what is now Lough Neagh. The earth that had been dug up and thrown at the giant by Finn McCool fell into the Irish Sea to become the Isle of Man, an island situated between Ireland and England.
Another interesting legend about Lough Neagh, especially from a geological perspective, is that it was said to have the ability to turn sticks into iron or stone. It was said that this phenomenon could only happen to a branch of holly after a period of seven years. If a stick of holly was stuck into the bottom of the lake, the part that was stuck in the mud would turn into iron, the part in the water into stone, and what lay above the water would remain a holly stick. P.W. Joyce, author of The Wonders of Ireland, speculated that the legend arose when pieces of petrified wood were found on the shores of Lough Neagh. It is said in the 1922 Ireland’s Own that he also believed the petrified wood was much older than Lough Neagh.
Lough Neagh wasn’t formed an overflowing magical well or an angry Irish warrior. It is actually the result of extensive dextral faulting in the Cenozoic which parted the earth to form a pull-apart basin. Dextral faulting is a type of transform fault, one in which the crustal plates slide past each other. Dextral faults exhibit a sense of right lateral motion, meaning if one plate was held stationary, the other plate would appear to move to the right relative to the stationary plate (Figure 1). The lake is underlain by an early Cenozoic aged fault that strikes NNW.
A pull apart basin is formed when there is a bend in a strike slip system. As the plates move past each other, the bend is extended and opens up in a zone of extension. It has been inferred that Lough Neagh is situated on a pull apart basin, as the lake has many of the characteristic features of this geologic phenomenon.
The Lough Neagh Conservation Project works to preserve the history and culture of the lake and provides informational resources to the public at their website here.