User:Mrchris/Geology of County Kilkenny

The geology of County Kilkenny includes the Kiltorcan Formation which is early Carboniferous in age. Most of the county is principally limestone of the upper and lower group, corresponding with the rest of Ireland. Bedrock geology information is available from original 1:10560 (six inch) field sheets and from the GSI bedrock report for the area (Archer et al, 1996).

The Kiltorcan Formation is located around Kiltoncan Hill near Ballyhale in the Callan and Knocktopher areas. It forms the uppermost part of the Old Red Sandstone and is the distinctive Upper Devonian-Lower Carboniferous unit in southern Ireland. It contains non-red lithologies, green mudstones, siltstones, fine sandstones and yellow sandstones. There is a fossil assemblage containing Cyclostigma and Archaeopteris and Archaeopteris hibernica.

A large area in the north and east contains beds of coal, surrounde by limstone strata, alternated with shale, argilaceous ironstone, and standstone. This occurs eastward of the Nore around Castlecomer, along the border with County Laois. It is generally accompanied by culm, which was used extensively for buring lime.

The main rock type in the vicinity of the Bennettsbridge is the Ballysteen Formation.

The formation is present in two forms; a dolomitised and an undolomitised portion. Approximately 30 m of shaley Ballysteen limestone overlies the dolomitised Ballysteen limestone. Water flows are derived from the dolomitised Ballysteen Formation and the town of Bennettsbridge use this as a water source. The bedrock aquifers have been affected by a large north-south trending fault which is believed to follow the Nore River channel. As a consequence, the Butlersgrove Formation abuts-against the dolomite to the west. On the southern side of a major syncline (downward fold in the rock mass) at the centre of which are the young rocks of the Slievardagh and Castlecomer Hills. The Ballysteen Formation dips at 5° to 6° north-westwards.

The main bedrock types in the vicinity of the Piltown/Fiddown comprise the Carrigmaclea Formation and the Kiltorcan Formation. The Carrigmaclea Formation underlies the Templeorum surface water catchment upstream of the springs. It consists of a sequence of quartz-cobble conglomerates, pebbly sandstones and crossstratified sandstones. There is a boundary between the Carrigmaclea and the lower units of the Kiltorcan Formation. The Kiltorcan Formation as a whole is a regionally important aquifer, with lower permeability shales, mudstones and siltstones are predominant close to the boundary with the Carrigmaclea Formation (Daly, 1994).