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Groundwater environments
Published in Ian Acworth, Investigating Groundwater, 2019
Secondary calcite may also be deposited by supersaturated meteoric waters (groundwater that precipitates the material in caves). This produces speleothems such as stalagmites and stalactites commonly found in cave systems. Figure 1.42 shows a typical stalagmite from Wellington Caves in New South Wales. These caves are developed in Ordovician limestone, part of the Lachlan fold belt.
Construction Methodology of Dam Foundation and Technology of Its Foundation Treatment
Published in Suchintya Kumar Sur, A Practical Guide to Construction of Hydropower Facilities, 2019
Stalactite is a very common crystalline deposit that is found to be hanging from ceilings of caves. Its formation starts when water drops hang on the ceiling and have lost their carbon dioxide in the air before falling, and a very little quantity of calcium carbonate gets deposited in the ceiling as a crystal and it gradually takes the shape of a fascinating crystal known as stalactite, which can serve as an attraction to tourists.
Surface Processes
Published in F.G.H. Blyth, M. H. de Freitas, A Geology for Engineers, 2017
F.G.H. Blyth, M. H. de Freitas
Water circulating underground helps to extend channels and caverns by solution, particularly in limestone formations; streams which once flowed on the surface disappear down swallow holes and open joints, Fig. 3.3, and continue their journey by flowing along bedding planes and joints below ground. In the Cheddar caves of the Mendips of S.W. England the former surface stream now has its course 15 to 18 m below the floor of the caverns, which are now dry. The Cheddar Gorge, 128 m deep at one point, is probably a large cave system which has become exposed at the surface by the collapse of its roof. As water charged with calcium bicarbonate trickles over the walls and drips from the roofs of caves, part of it evaporates and calcium carbonate is slowly re-deposited as loss of carbon dioxide occurs (i.e. the equation given on p. 32 is reversible). In this way masses of stalactite, hanging from the roof or coating the walls of a cave, are formed, sometimes making slender columns where they have become united with stalagmites which have been slowly built up from the floor of the cave, onto which water has dripped over a long period of time. Sheet stalactite coats the walls of many caverns and may be coloured by traces of iron and lead compounds.
Improving Australia’s flood record for planning purposes – can we do better?
Published in Australasian Journal of Water Resources, 2020
KJ Allen, P Hope, D Lam, JR Brown, RJ Wasson
Speleothems are formations in caves – stalactites or stalagmites – formed by the deposits of minerals from dripping water. They are ideal for the reconstruction of terrestrial hydroclimate (Lachniet 2009). Typically, three tools are used: δ18O, luminescent bands (Shen et al. 2013) and physical deposition of detritus from cave flooding (Denniston et al. 2015; Denniston and Luetscher 2017). In Australia, speleothem-based flood records from north-western Australia, tropical Queensland and South Australia exist. Importantly, Denniston et al. (2015) found that a sharp increase in extreme rainfall events from ~1890 co-occurred with the expansion of grazing, highlighting the need to consider anthropogenic land-use changes when interpreting records.