Heritage Sites of Co. Cavan
Cavan Courthouse, Farnham Street, Cavan
The neo-Classical courthouse on Farnham Street is situated on what used to be the market square. Building commenced in 1824 under the superintendence of Williams & Cockburn of Dublin to the designs of William Farrell. It cost £11,000 – 12,000 to build.
The ashlar façade and single-storey tetrastyle Tuscan portico is of Latt sandstone. This yellowish-grey, medium-grained Carboniferous sandstone is siliceous, durable and easily worked. It was extensively used in buildings in Cavan town. The squared rubble side elevation is of Drumelis limestone, a fine-grained, grey Carboniferous limestone, and the round-headed window openings are dressed with cut Latt sandstone.
Alterations and additions to the building occurred in 1866. In the early 1930s the County Council made the decision to remove British emblems from the building, leaving the plinth at the top front of the building bare. A canon, presented to the town after the Siege of Sebastopol at the command of Queen Victoria, which stood on the front lawn, was also removed. The building was extended at the rear c. 1985; concrete, brick and slate were employed.
- Kevin V. Mulligan, The Buildings of Ireland: South Ulster (2013), pp. 252.
Geology of Co. Cavan
The oldest rocks in County Cavan are 417-495 million years old [Ma] and consist of mudstones and volcanic rocks. At that time Ireland lay beneath a deep ocean on the edge of an ancient continent made up of Scotland, north America and the north of Ireland. A huge ocean separated this continent from the rest of Ireland, England, Wales and Europe. Over millions of years this ocean closed and the two ancient continents collided, heating and deforming the rocks to form slates. The same rock types occur from Longford, through Cavan, County Down and into the Southern Uplands of Scotland. Plate tectonic movements closed the ocean and the ocean floor rocks were faulted in slivers against the northern side. County Cavan now has these slivers of slate and sandstones stacked up across the southern half of the county. Only where a few graptolite fossils occur in the black slates can we work out the actual age and structure of the rocks.
As the ocean finally closed around 400 Ma bodies of molten magma moved up through the Earth’s crust, cooling slowly to form granite. Just one small area of granite is known from the county at Crossdoney, a little south-west of Cavan town. The northern half of the county is composed of Carboniferous rocks; firstly limestones deposited in a shallow tropical sea with lots of animal life. The sea then shallowed and was filled in with delta sediments, which became sandstones and shales. These rocks occur in the uplands around Lough Allen and especially in the Cuilcagh Mountain area. In the surrounds of Cuilcagh Mountain there is a lot of limestone exposed, which has developed karstic features since the Ice Age including many caves and potholes and limestone pavements.
Ireland lay in the northern tropics during the Permian and Triassic periods and the sedimentary rocks from this time, preserved around Kingscourt in Cavan (also in Monaghan and a little in Meath), record deposition of sediments in arid deserts and temporary seas that were periodically dried out to precipitate thick evaporite deposits of gypsum. The subsequent Jurassic, Cretaceous and Tertiary periods have largely left no trace as rocks preserved on land. It is inferred that Ireland was mostly a land area, subject to weathering and erosion, which supplied only offshore basins with sediment.
Map legend: Geological Map of Limerick (based on GSI 1:1,000,000 map 2003). Pink: Ordovician; Red: Granite; Pale green: Ordovician & Silurian; Dark Blue: Lower Carboniferous sandstones; Light blue: Lower Carboniferous limestone; Dark green: Upper Carboniferous shales; Brown: Permian & Triassic sediments.