| Origin of
the Irish Limestone Industry:
There is a long, well
documented history of the use of limestone as a construction material in Ireland. During
the Neolithic and early Bronze ages, elaborate Burial Cairns were constructed in the
northern parts of the country often from the local limestone. These were large mounds,
many containing upwards of 70,000 cubic metres of earth, with an open chamber in the
centre. The so-called portal dolmens utilized large blocks, some weighing up to 100
tonnes, which were balanced on stone pillars to form the chamber. The contemporaneous
passage graves incorporated much more elaborate engineering concepts. The central
chamber was approached by a narrow passage with stone lintels forming the roof. In
some cases, such as Newgrange in County Meath, this passage was precisely alligned to
permit the sun to shine and, through a notch over the doorway, illuminate the passage and
inner chamber at dawn on Midwinter's Day.
The
central chamber in many passage graves is so large that a corbelled roof had to be
constructed. Apart from the sophisticated engineering, the other characteristic of
the passage graves is the extensive carving of the actual tomb stones. Complex
geometrical motifs including circles, spirals, triangles, diamonds and herringbones can be
found and probably represent the earliest stone carvings in Ireland.
The carving of stone became more sophisticated in the Iron
Age and impressive examples of the art can be seen in many places such as the Turoe Stone
at Ballauh, Loughrea in County Galway. This shows the curvilinear patterning that was
to become the hallmark of much of the subsequent Celtic work.
The arrival of Christianity heralded a new era for both
stone cutting and stone carving in Ireland. The stone masonry of this era probably
reached its pinnacle around 1000 A.D. with the construction of the tall slender stone
towers that are a feature of many Irish towns.
Norman influences were
reflected in the architecture from the latter part of the 12th century. Romanesque
churches with round headed doorways, chancel arches and windows; many of which had
elaborate decorative motifs; required highly skilled stone masons and carvers.
Many large castles and monasteries, such as Jerpoint in
County Kilkenny, were constructed between the 12th and 15th centuries. A number of
the buildings from this era have become monuments that are now in the care of the state.
The size and scope, as well as the abundant use of carving, provides evidence of the
skills of the masons as well as the durability of the local limestone.
The importance of the stonemason, who was often also the
architect, was recognised in 1410 when the Stonecutters Guild of Ireland was granted its
Charter.
Brick became an important construction material from the
17th century but local limestone continued to be the material of choice in public
buildings and the bridges and locks of the canals.
Although the traditional
skills of the Irish stone mason continued into the 20th century, this was often restricted
to the carving and lettering of headstones. As the grain structure of the Irish
limestones was suitable for the working of fine detail, the material continued to be of
great importance for these applications.
The renaissance of the Irish Limestone industry began
during the latter half of the 20th century. The introduction of commercially viable,
diamond based cutting equipment revolutionised the extraction and processing of limestone
and the Irish industry was quick to embrace this advanced technology.
When limestone is used as a building material, the physical
properties and the inherent structure of the material governs the applications and the
manner in which it can be used. Irish limestone has two recognisable facies and
although both have always been worked, the technology of the period has always favoured
one type of stone.
Until the early part of
the 20th century, the extraction and processing of limestone was labour
intensive. The deeper water facies tend to have thin regular bedding that simplified
the extraction of uniform thickness slabs. When the principal applications were
ashlar or headstones, the uniform thickness made dressing straightforward and this
material dominated the industry. Although the limestone could occasionaly be quite
siliceous, this caused few problems for the production of ashlar. Almost all the
quarries had some thicker beds that were capable of supplying material for lintels and
sills. The more massive limestones were also worked but often the extraction was
limited to the slightly weathered upper zones that could be extracted with relative ease.
The latter part of the 20th century was marked by a major
change in construction techniques. Slim reinforced concrete beams became the main
structural component in buildings and ashlar was displaced by thin non-loadbearing
cladding panels. The new diamond technologies that became available about the same
time enabled suitable materials to be cut into thin panels and the massive crinoidal
limestones offered the ideal medium for this equipment.
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