Turloughs and tiankengs: distinctive doline forms


John Gunn


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Speleogenesis and Evolution of Karst Aquifers

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Tiankengs lie at one extreme of the collapse doline spectrum, and a key question is whether there is a distinctive ?tiankeng process? or whether the distinction is purely morphological. At the opposite end of the doline spectrum, the turloughs of Ireland are broad closed depressions with seasonal lakes. They may be differentiated from poljes by their smaller dimensions, gentler surrounding slopes and processes of formation. In particular, turloughs are only found in areas where there are glacial deposits and are, at least in part, glaciokarstic landforms whereas poljes occur in many climatic zones and their locations frequently demonstrate a structural influence. Turloughs have been recognised by the European Union as special karst landforms with a distinctive vegetation assemblage, although the term is not widely used because, with one exception, they are confined to Ireland. There are clear parallels with ?tiankeng? the majority of which are in China and which are distinguished from collapse dolines by their large size, and special processes of formation. It is argued that the terms ?turlough? and ?tiankeng? should both become established in the karst geomorphology lexicon.


Turlough, Tiankeng, Karst, Ireland, Terminology

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