Marechal Jean-Christophe

Senior Hydrogeologist

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1039 rue de Pinville
34000 Montpellier

Stalagmites growth

Stalagmite formation: new findings

By analyzing the trajectory of water drops falling from cave ceilings, we have determined a relationship between the widely varying widths of stalagmites and the geometry of underground cavities.
Our study published by the Royal Society Proceedings, bringing together researchers from the University of Liège, the University of Bordeaux, the University of Montpellier and the Bureau de recherches géologiques et minières, has clarified how stalagmites are formed. By analyzing hundreds of videos of falling water droplets at very high frame rates (5000 images per second), they discovered that the width of the stalagmites depended on the height of the cavity ceiling. The drops of water that fall to the ground and precipitate the calcite that forms stalagmites do not follow a constant trajectory: their points of fall vary constantly, and this dispersion explains the width of the stalagmite that is formed.
The falling drops of water create a micro-vortex which, in response, modifies the trajectory of the drop. The phenomenon was tested in the laboratory and mathematically modelled. "We can now deduce the geometry of the cave at the time the stalagmite was formed," explains Jean-Christophe Maréchal, Research Director at BRGM and co-author of the study. The research group's work could thus help to understand the very diverse shapes observed in cavities. Scientists are also looking to use these new results to study paleoclimates, whose information is trapped within the concretions.


A drop does not fall in a straight line: a rationale for the width of stalagmites

J. Parmentier, S. Lejeune, M. Maréchal, F. Bourges, D. Genty, V. Terrapon, J.-C. Maréchal, T. Gilet

Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 475, 2019 Nov, p. 20190556


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