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The Marble Arch Cave system is a maze of cave passages totaling 6.5 km in length with 1.2 km open to the public. In 2001, Marble Arch Caves became a European Geopark and part of the UNESCO European Geopark Network. www.europeangeoparks.org
340 million years ago, a shallow tropical sea teaming with sea creatures, covered the landscape of Fremanagh. This has been preserved as limestone which includes the remnants of many of those sea creatures including corals, sea lilies and many other shells. The limestone at the surface has been ravaged by the elements resulting in rugged but spectacular scenery including limestone pavement and dry valleys. The elements have not only left their mark above ground, but underground a series of caves over 6 km in length and 55 m below the surface have been scoured out of the limestone.
Rain water is naturally acidic and becomes more acidic as it passes through soil. When this weak acid water passes through cracks (vertical joints and bedding planes) in limestone it dissolves the rock just as salt and sugar dissolves in water, only much more slowly. Over thousands of years rainwater and mountain streams dissolve or erode the rocks, widening the cracks until they become caves. Three rivers flowing off the sandstone slopes of Cuilcagh Mountain now sink into these enlarged cracks in the limestone and help to form the large underground network of passages that criss-cross the mountain.
Weathering is the breakdown and decay of rocks on the earth’ surface. The wearing away of limestone rock is an example of chemical weathering. Limestone consists mostly of the chemical calcium carbonate, derived from the skeletal remains of countless tiny marine organisms. The rainwater is a weak acid that slowly dissolves the limestone. The rainwater slowly opens up cracks in the surface, wearing out holes that eventually lead down to a maze of huge caves linked by tunnels.
Stalactites are formed when water containing a lot of calcium carbonate drips down for the ceiling of a limestone cave. The water gradually deposits calcium carbonate to form hanging icicle-like structures called stalactites. Stalagmites are the opposite of stalactites. They are columns of calcium carbonate deposited by dripping water that grow upward from the floors of the caves. There are several types of stalactites and stalagmites in the Marble Arch Caves, (cave cauliflower, curtains, flowstone, etc.)
Early cave exploring was a sport for the daring adventurers. It did not gain scientific respectability until the end of the 19th century through the methodical work of Edouard-Alfred Martel (1860-1938). Martel devoted all of his vacation time to cave exploration while training as a lawyer completing his legal studies in 1883. His passion for cave exploration soon overtook his law practice and in 1899 he gave up law altogether and became a speleologist, teaching at the Sorbonne, writing and consulting.
Martel first explored the caves in 1895. He was attracted to the area by stories he had heard of big limestone hills and rivers that disappeared into gaping cave mouths and infested with ghosts and spirits. This was exciting news for a cave explorer as there were likely to be large, hidden caves left unexplored by fearful local country people.
Martel wrote, “Rather will I speak of the vast grottoes, miles in extent and hung with enormous stalactites, underground rivers never yet traced, subterranean lakes overhung with canopy of sparkling crystals, beautiful as Aladdin’s cave, and whole worlds in the bowels of the earth, dark and hidden in the ordinary way, yet transformed into an appallingly magnificent series of glaring palaces under the intense glow of magnesium light.”
At that time, entrance to the Marble Arch Caves was through a large pot-pole, a hole in the ground that leads to an underground cave. When Martel first entered the Marble Caves he entered via a rope. He would place a cannon ball at the end of the rope to judge the depth of the pot-hole before descending into the unknown.
When Eduoard Martel and a naturalist called Lister Jameson first explored Marble Arch caves they used a small collapsible canvas boat along with paddles, and candles and magnesium flares for lighting!
Today visitors enter the caves through a series of steps. On your visit, the ancient origins of the caves many millennia ago will be explained.
Over 300 million years ago, in the Carboniferous period, Fermanagh was covered by a shallow, tropical ocean. Millions of shells of tiny sea creatures fell to the ocean floor after death. Compaction built up all these Calcium Carbonate shells into a 'blocky' rock called Carboniferous Limestone.
Later on, plate action saw mountain building and continents colliding, with the former ocean floor uplifted out of the sea to form the broad plateau which is the limestone landscape of Ireland.
Later still, the action of ice exposed areas of limestone, allowing rivers to attack the carboniferous limestone via its joints and bedding plants. Joints are the vertical cracks and bedding planes are the horizontal cracks in the limestone.
After the cave has been opened by the action of water, creation of some of the other features of the Marble Arch Caves begin. Water, containing dissolved limestone (calcite), drips or runs from the cave roof. Calcite is deposited as stalactites, stalagmites or other features.
When all this has happened you are left with a typical Karst landscape. The Marble Arch caves and nearby Cuilcagh Mountain Park are such landscapes.
In order to claim the Marble Arc Caves EarthCache:
1. It is not a requirment for posting that you take a picture of yourself with your GPS in front of the sign at the road entrance to the Marble Arch Caves. This is a completly optional requirment.
2. There is a 1.5 m (apx) cast iron marker in front of the information centre. What does the marker signify?
3. Explain how Martel determined the height of the caves.
It is not necessary to take a tour of the cave to claim this cache but I would highly recommend it as a fascinating adventure.
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