Bulletin of the National Speleological Society - ISSN 0146-9517
Volume 22 Part 1: 77-84 - January 1960
A publication of the National Speleological Society
Geometrical Basis for
Arthur L. Lange
The shapes of cave structures can be a key to understanding the evolution of the cave, since they are the result of erosive and depostional processes acting on the cave boundaries. Any future outline of a uniformly dissolving or encrusting cross section of wall, ceiling, or floor is generated by a circle rolled with its axis everywhere in contact with the initial outline. The envelope described by the circle representes the new contour, and the radius is dependent on the mass transfer rate and the duration of the action. In the case of the three-dimensional body, a generating sphere will yield the correct form. This procedure is a geometrical interpretation of the differential equations expressing the event.
Sharp projecting corners will remain sharp while dissolving and will round off when encrusted. Inside corners will round off under solution and remain sharp during depostion. The resultant topographies of complex wall pattern are typical of the scaloped solution-work and bulbous encrustation found in caves where corrasion, gravity, and other directional agents have not modified the basic mechanism.
Plane walls, inundated stalactites, and right-angled ceiling blocks serve as examples of simple geometrical structures. Solution pockets, mammillary crusts, domes, gours, crusted strands, and wall niches are examples of more complicated forms. A cave system flowing normal to a cross seciton and an evenly circulating water body or film are cave media in which the process of uniform mass transfer can be closely approximated.
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26 July, 2002 14:37
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