Ballysudden
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Geology & landscape
Geological Feature: Rock Outcrop · Geological Period: Carboniferous · Rock Type: Limestone
Landscape processes: Fluvial
Description
Ballysudden Carboniferous stratigraphy The Carboniferous outcrop at Ballysudden exposes over 100m of strata in a continuous section. It is the best section of the late Visean rocks of the Armagh Group in Northern Ireland; these are some 335 million years old (M.y.). The variety of lithologies representing a wide range of facies is remarkable and some of the sedimentological structures preserved are spectacular including ancient solution features in limestone. The succession of lithologies were generally deposited either in shallow marine or terrestrial environments. The former setting resulted in the formation of shallow water limestones interbedded with thin sandstones. The rock series is richly fossiliferous in places, with brachiopods, colonial and solitary corals and microscopic groups present. Assessment of both macro-and micro-fossil evidence has been used to determine the ages of much of the sequence as well as the approximate position of the Asbian - Brigantian boundary, dated at some 331 M.y. Emergence and exposure of the former limestone seabed to terrestrial conditions allowed soil development and solution of the limestone to commence. This resulted in the formation of potholes and other solution hollows which can attain substantial sizes within the site. These appear to be among the finest Carboniferous palaeokarst features exposed anywhere in the British Isles. Fluvial channels infilled by sand debris occur only rarely but prove the existence of former rivers. https://www.daera-ni.gov.uk/publications/ballysudden-assi