Heritage Sites of Co. Kildare
Castletown House, Celbridge
Castletown House is the finest Palladian house in Ireland. Built over a decade from 1719 for William Conolly, the Speaker of the Irish House of Commons, it was designed by Sir Edward Lovett Pearce. Some input into the design may have been received from Alessandro Galilei and Thomas Burgh; the latter is best known for his Old Library in Trinity College. The initial building work was carried out by the contractor John Rothery. Later activities included the completion of the staircase in 1795, executed in Portland Stone by the Dublin craftsman Simon Vierpyl. He also worked on City Hall and the Marino at Casino.
Edenderry Limestone is utilised for the front façade upper stories, colonnade columns and window architraves on wings. This is a pale, silvery, oolitic limestone, which on close inspection can be seen to be slightly fossiliferous and contains small dark shelly fragments. Interestingly, the fluted columns of the side colonnades are split vertically into half drums which suggests that the beds in Carrick quarry north of Edenderry, from where the limestone was extracted, were not thick enough to allow for full cylinders to be worked. When the Office of Public Works restored parts of the façade they reopened Carrick quarry and extracted 35 tonnes of limestone.
A darker Calp Limestone is used for the front façade basement story, the side elevations and the facings of the two pavilions, and provides a more rustic and varied tonality than does the pale oolitic limestone. The Calp was quarried locally, either on the estate (one field is still called the Quarry Field) or more likely was transported from quarries situated to the east at Lucan and Palmerstown which were the major sources of Calp in the early 1700s. Calp Limestone is very distinctive, being muddy, generally lacking in fossils and having an almost black colour when fresh or a warm brown colour resulting from long-term weathering. When left rough, as in parts of Castletown, it generally takes on a conchoidal fracture. Close examination of this stone also shows that it has been burrowed before it became lithified, probably by annelid worms working their way through the muddy limestone seeking nutrients.
Bishop Berkeley, writing to Sir John Perceval in 1722, commended the use of Irish craftsmen and materials, especially Irish marbles for the chimneypieces. In actually the only Irish material utilised for this purpose was polished Kilkenny limestone; the hallway chimneypiece is the largest and lesser examples are found in the Brown Study, Butler’s Pantry, Map Room, and Lady Kildare’s Room. The Kilkenny stone contains tiny brachiopod shells and solitary corals that reveal it to having been deposited in warm shallow water conditions. The remaining chimneypieces are of Italian white Carrara marble and include those in the Red Drawing Room; Green Drawing Room with beautiful double iconic columns installed in 1768; and elsewhere, some of which are enhanced with insets of golden Sienna marble or black Kilkenny limestone.
In a building such as Castletown the main hallway creates for visitors the initial visual impression of the splendor of the house. Even the floor is decorative, being a diagonal checkered arrangement of Kilkenny black limestone and creamy Portland stone framed in a thin band of the black stone. Both the main staircase and the west back stairs are in Portland stone.
Elsewhere York flagstones floor the Butler’s Pantry; a very unusual brown oncolitic limestone paves the west corridor; Irish grey crinoidal limestone, which is a modern replacement, is found in the east corridor; black fossil-bearing goniatitic Carlow flagstones make up the east back stairs; and modern grey slate is in the basement.
Within the stables good use of cut and dressed stone was employed: columns of Edenderry Limestone with reddish sandstone capitals separate the stalls and in recent years a modern floor at the entrance room to the stables is laid with sawn slabs of Irish Mississippian limestone.
- Patrick Walsh (2007) Castletown, Co. Kildare. OPW, Dublin.
Geology of Co. Kildare
The oldest rocks in Kildare are of Ordovician age (490-450 million years ago [Ma]) and are in the Kildare Inlier (an area of older rocks surrounded by younger rocks). Silurian rocks (430 Ma) also occur there and in a wide belt in the southeast of the county. All these rocks were formed under an ocean that separated two continents. At the Chair of Kildare and at the Hill of Allen there were two volcanic islands for a short time. The hard volcanic rocks that erupted are more resistant to erosion and have become isolated hills in the plains of Kildare. During eruption of the volcanoes the surrounding shallow waters were populated by marine animals and some of the rocks then formed now contain occasional fossils.
As the ocean closed the mud and sand deposited in the Silurian was converted into rock and became deformed and uplifted as part of a mountain range, not just in Kildare but throughout Ireland. Around 400 Ma during the Devonian the rocks were then affected by a chain of plutons of granite that were intruded throughout Leinster. The Tullow Granite is found in the south of the county but is shared with Carlow and Wicklow. It was formed beneath the crust and the molten igneous rock cooled slowly. The rocks that covered it have since been eroded away.
General subsidence permitted the sea to invade the lower ground from the south during the Carboniferous period. The depth of the sea and type of bottom varied from place to place, producing a variety of limestone (carbonate) sediments at any one time; for instance, oolites, which form in only very shallow water occur mainly around the present Kildare Inlier. After a time carbonate mud banks or “reefs” (Waulsortian Limestones) developed as upstanding mounds on the sea floor across parts of the Kildare area (and much of the midlands of Ireland). Growth of these mounds was probably due to the rapid accumulation of fine carbonate mud produced by unknown organisms. A rich fauna, including sea lilies (crinoids) and varying micro-organisms, lived on the mounds.
Volcanic activity also occurred near Edenderry during a period of subsidence and faulting. The Carboniferous coalfield rocks (like those at Castlecomer) may once have covered Kildare but have been eroded away since. During the Tertiary period tropical weathering may have affected the landscape but the biggest changes were during the last 1.6 million years when ice ages came and went. The last one ended about 10,000 years ago and imparted some key geological characteristics to Kildare. Meltwater from the ice sheets deposited enormous volumes of sand and gravel, up to 70m thick in places such as the Curragh. After the ice melted big depressions surrounded by glacial deposits formed shallow lakes where the great raised bogs of the midlands, like the Bog of Allen, built up. Likewise, spreads of blanket bog that cover the upland areas of the county to the east formed in the 10,000 years following the end of the Ice Age. The alluvial deposits of the rivers, including the Liffey and Barrow, were also deposited during this period.
Map legend: Geological Map of Limerick (based on GSI 1:1,000,000 map 2003). Pale pink: Ordovician; Turquoise: Ordovician volcanic rocks; Pale green: Silurian; Dark pink: Granite; Beige: Devonian sandstones and conglomerates; Pale blue: Lower Carboniferous limestone; Dark green: Upper Carboniferous shales.