There are many decorative rocks marketed as ‘marbles’ when they are in fact limestones. Marble and limestones may share the same origins, but are created under different conditions. If limestone is subjected to a lot of heat and pressure, it turns into marble. Marble has none of the original features and structures of the limestone it evolved from and consists almost entirely of calcium carbonate in other crystallised forms.
St Fin Barre’s Cathedral is an impressive host of many limestones.
Venturing inside the Cathedral allows us to shake things up a bit. Around the interior are pillars and ornamental structures made of colourful and patterned rocks which have taken on all sorts of colours. One of these rocks is red and orange with crinoid fossils in it. This is the Cork Red Marble, and it also exists as an ornamental rock in other areas of the City. Here it is part of a series of other “marbles”. Note that these rocks are actually not marbles but are still limestone. In fact, the Cork Red Marble was created in the shallow tropical seas when underwater landslides cascaded down to the seafloor and created jumbled, unsorted deposits of limestone and seafloor
. The inside of the cathedral reveals many different kinds of building stones from around Ireland and beyond. Decorative ‘marbles’ and a real marble inside St Fin Barre’s Cathedral. Inside the Cathedral there are other forms of limestone that are referred to as ‘marbles’. The black ‘marble’ has been extracted from Kilkenny, the blue ‘marble’ is from Northern Ireland, and finally the white ‘marble’ is from the Pyrenees. That being said, there is actually a real marble here, and that is the green marble from Connemara. Due to the continental collisions during the Caledonian orogeny (if you don’t know what this is, you can read the section on Cork City’s geological history), limestones in the Connemara area were subjected to enough heat and pressure to turn them into marbles.
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