Karst Route

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Aire and Candeeiros hills are the most important repository of the calcareous formations in Portugal and this is the first reason of its classification as Nature Park. Karstic morphology, the nature of the vegetation, the network of underground watercourses, a specific fauna and intense activity in the field of stone extraction are other important aspects. It is recognized that the Estremenho Limestone Massif is the most important karst region of Portugal. This is due, first of all, to its individualization in the landscape and, above all, the existence of fields of lapiaz, areas with dolines, uvalas and more complex depressions, karst depressions typifiable as Polje, one of which (Minde's) presents a so complete set of endokarst and exokarst characteristics that can be considered an example of the definition of "polje", great number of caves, avens and extensive subterranean aquifers drained by important springs. AVEN, SWALLOW-HOLE, SHAFT or NATURAL WELL – from the Arab al-gar (hole). Natural well in limestone or volcanic terrain, resulting from the falling of caves ceilings or vaults as well as sinkholes. DOLINE (also known as SINKHOLE) - a closed surface depression draining underground in karst landscape. Dolines are usually more large than deep, "bowl-shaped" and can have only a few or many hundreds of meters in diameter. KARST- a distinctive topography that indicates dissolution of underlying soluble rocks by surface or ground water in areas of easily soluble rocks. The name comes from Karst, a region in Slovenia with this type of landscape, characterized by caves, underground drainage and sinkholes. LAPIAZ or KARREN FIELD- common landscape in limestone areas, with many grooves due to the limestone dissolution by rainwater along fractures and cracks. POLJE – limestone relief form consisting of an elongated and long depression generally flat bottom. Often it has a very steep slope corresponding to a fault. In rainy periods it often becomes a temporary pond. UVALA – a large closed depression formed by the coalescence of 2 or more dolines.