Bulletin of the National Speleological Society - ISSN 0146-9517
Volume 35 Number 1: 1-9 - January 1973

A publication of the National Speleological Society

Minimum Diameter Stalagmites
Rane L. Curl


The theory of Franke setting forth the factors controlling equilibrium stalagmite diameter at high drip rates is extended to the low-flow situation in which a minimum diameter is obtained. It is shown that the minimum cross-sectional area for a stalagmite must be determined by the ratio of incident drop volume to the thickness of the water film at the apex. Reasonable values for these quantities predict a minimum diameter of about 3 cm, close to that observed. An approximate model, the primary feature of which is the repetitive tranient relaxation of the tip-growth of the stalagmite between drop impacts, is used to bridge between the high and the low flow regimes. The importance of presently little-known factors involving drop impact, mixing, crystaliztion from solution, and film flow in determining equilibrium stalagmite morthology are brought out.

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