Glossary of Technical Terms

Aquifer A rock that stores and transmits water in significant quantities.

Carboniferous The geological time period from 355 to 290 million years ago when most of our limestones were laid down (refer to table in 'Ancient karst or palaeokarst in Ireland' section).

Clint A block of limestone on a limestone pavement bounded by open grikes.

Cretaceous The geological time period from 135 to 65 million years ago (refer to table in 'Ancient karst or palaeokarst in Ireland' section).

Devonian The geological time period from 410 to 355 million years ago (refer to table in 'Ancient karst or palaeokarst in Ireland' section).

Doline A small to medium sized closed depression, a few metres to a few hundred metres in diameter and depth. Dolines are formed by slow, concentrated solutional removal of rock in an area, from the surface downwards, or by the collapse of overlying rock into a cave or chamber beneath (collapse doline). Dolines function as funnels, allowing point recharge of the karstic aquifer. In the USA, dolines are termed sinkholes.

Dolomite Carbonate rocks which have undergone chemical changes resulting in the replacement of some of the calcium by magnesium. Can be highly karstified in places.

Estavelle A karst feature that can function as a spring or as a swallow hole depending on underground water levels.

Grike A fissure (crack or joint) in the limestone bedrock that has been widened, sometimes to tens of centimetres, by the dissolving action of rainwater.

Jurassic The geological time period from 205 to 135 million years ago (refer to table in 'Ancient karst or palaeokarst in Ireland' section).

Karren, Karrenfield Small (millimetres to a few metres) solutional channels, hollows or enlarged fissures on the surface of the rock. Extensive exposures of bedrock with such features are called karrenfields.

Karst An area of limestone or other highly soluble rock, in which the landforms are of dominantly solutional origin, and in which the drainage is usually underground in solutionally enlarged fissures and conduits.

Limestone Pavement Bare limestone surface from which soil and loose rocks have been stripped – usually by relatively recent ice erosion during a glacial period.

Ordovician The geological time period from 510 to 438 million years ago (refer to table in 'Ancient karst or palaeokarst in Ireland' section).

Polje A large, relatively flat floored enclosed depression bounded by steep sides, with a floor area of one to several hundred square kilometres. Commonly, sediments blanket some or all of the floor.

Quaternary The geological time period from 1.6 million years ago to the present day which includes the Ice Age (refer to table in 'Ancient karst or palaeokarst in Ireland' section).

Speleology The scientific study of caves.

Stalactite The mineral calcite (calcium carbonate) deposited in crystalline form from lime-rich dripping waters on to the roof of a cave. Stalactites grow downwards to form tapering pendants.

Stalagmite Calcite deposits as per stalactites but with the deposition taking place where trickles of water splash on to the cave floor. The resulting deposits grow upwards to form a column.

Swallow hole, Pothole The point at which a surface stream sinks underground.

Tertiary The geological time period from 65 to 1.6 million years ago (refer to table in 'Ancient karst or palaeokarst in Ireland' section).

Turlough Seasonal lakes found in the lowland karsts of western Ireland. They often fill and empty via estavelles.

Waulsortian Limestones A group of limestones of Carboniferous age which were laid down as massive calcareous mud mounds. Found in many parts of the country.