The Pigeon Hole
The Pigeon Hole, or Poll na gColum as it is known in Irish, is a cave located between Lough Corrib and Lough Mask just outside of Cong in the west of Ireland. It’s a popular destination for walkers and tourists alike. A steep flight of limestone steps leads down to the mouth of the cave, a fairly large chasm over 12 feet wide (1) covered in bushes and ivy where the pigeons for which the cave is named like to nest.
Where Irish legend is concerned, this is the site of one of the most famous legends on the mysterious properties of caves. This cave is said to be home to a sacred trout, “the fairy trout,” which, according to legend, avoided bait and evaded capture.
“The White Trout” (2)
The legend begins with a beautiful young woman who lived in a castle by the lake (most likely Lough Corrib or Lough Mask). She was set to marry a king’s son, but as fate would have it, the prince was murdered before they were wed. Heartbroken, the young lady went mad with despair and then disappeared unexpectedly – taken away by the fairies, it is said.
After a while, a white trout appeared in the illuminated portion of the subterranean river. The townspeople had never seen such a trout and rumors spread like wildfire. It was fable to be a fairy, and given the utmost respect. But in time, a “wicked soldier” came to put the rumors to the test. He decided to catch the trout and fry it up for dinner. He caught the fish and brought it home without a problem. But when he put it on the pan, he began to realize that the fish would not cook. After flipping the trout from side to side in the frying pan to no avail, he decided to eat the fish anyway, even though it showed no signs of being cooked. As he put his knife to the fish, it screamed, leaped from the pan to the floor, and transformed into a beautiful young woman.
She held out her arm to show the soldier where he had cut her arm with his knife and explained that she was waiting for her true love in the river. She demanded he renounce his evil courses and take her back to the river. In the blink of an eye, the woman disappeared and in her place laid a small, white trout. The soldier quickly put the trout on a plate and rushed to the cave to put her back into the river. When he did, the river turned blood red momentarily. To this day it is said that one can find a white trout, with a little scar where it was cut, swimming in the sunny part of the river.
The Pigeon Hole is a large cave that opens up to reveal a subterranean stream in Carboniferous limestone. The water in this underground stream flows from Lough Mask into Lough Corrib. Interestingly enough, Lough Mask has no natural drainages on the earth’s surface (3); all of the water is drained out of the lake through underground rivers and streams. As the water flows from one lough to another, it surfaces in caves such as Poll na gColum.
This cave is the result of what is known as karst topography. Karst topography is a unique type of landscape that develops as a result of chemical weathering processes in limestone, a sedimentary rock that is made up of calcium carbonate, CaCO3. Calcium carbonate is very soluble in acidic solutions such as rainwater which is slightly acidic with a pH of 5.6 (4). When it rains, limestone begins to dissolve, setting off a positive feedback loop: rain dissolves the limestone along points of weakness (bedding planes); this creates larger passages within the rock; this allows more rainwater to enter and be stored in the limestone; this dissolves and erodes the rock even further (5).
(1) Geology of Cong and The Neale from Irish Tourist Association Survey, 1945 . Web.23 Oct. 2012. http://www.mayolibrary.ie/en/LocalStudies/IrishTouristAssociationSurvey/CongandTheNeale/Geology/PDFDocument,16120,en.pdf
(2) Lover, Samuel. Legends and Stories of Ireland. New ed. London: H.G. Bohn, 1853. 40-44. Print.
(3) “Walk 2: Underground Rivers & Dry Canal .” Geological Survey of Ireland. Web. 23 Oct. 2012. <http://www.gsi.ie/Education/Sites+Walks+Field+Trips/Walk+2+Underground+rivers+and+dry+canal.htm>.
(4) Ophardt, Charles E. “Acid Rain.” Virtual Chembook. Elmhurst College, 2003. Web. 23 Oct. 2012. <http://www.elmhurst.edu/~chm/vchembook/190acidrain.html>.
(5) “What Is Karst?” The University of Texas at Austin, Web. 23 Oct. 2012. <http://www.esi.utexas.edu/outreach/caves/karst.php>.