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Geyser Stalagmites

(Translated by M. Luckwill)

The Gran Caverna de Santo Thomas is situated in the Sierra de Quemado, in the province of Pinar del Rio and its ten and a half miles of passages make it the largest underground system in Latin America.  In 1955, Professor Antonio Nunez Jimenez and his party were exploring the system when they came across an unusual formation ‘never before reported in the New World’.  Over the rock floor they saw several stalagmites, conical in shape, and in whose tops appeared craters similar in shape to those of volcanoes.  These were a notable discovery in the field of speleology for they were not at all like the solid structures formed from water drops falling from the roof and slowly building up a large deposit.

At first they thought their discovery would have the following explanation: after the formation of a normal stalagmite by the drop process, the solution, having lost its carbonate content, would be acid and this acid solution, when dropping onto the stalagmite, would produce a hollow crater in them.  However, this hypothesis was rejected for, of the 234 stalagmites studied, the immense majority had neither stalactites nor water drops above. Also a few of the formations had a crater, not at the top, but on the side the side of the stalagmite which clearly indicated that they had not been formed by any falling water.

Their curiosity grew when they observed new characteristics in the formations which also compared with the big volcanoes on the earth's surface, a  more careful examination of the stalagmites showed them that the edge of the little craters possessed marks which seemed to indicate that the force which made them came from the inside of the stalagmite and proceeded outwards.  A microscopic analysis showed that the cones were formed from a porous mass of calcite very different in structure from that associated with the normal process of stalagmite construction.  They also found together with the Calcite, intrusions of Limonite and clay impurities.

It seemed, therefore, that the solution which had formed these deposits had been in the form of geysers and jets of water which had opened up fissures in the cave floor and left sediment of cones of calcite around the water vents, a process similar to that of volcanoes.

A search of the caving literature of the world over a period of years verified that only in the Grotto of Arragonite in Zbrasov, Czechoslovakia had such formations been reported.  There is no doubt that Cuba is the second country in the world to possess these geyser stalagmites.

As in the Czechoslovakian caves, the geyser stalagmites are aligned above a clearly visible fissure in the passage floor known as the Salon y del Abono.  The largest of them is nearly five feet in height, with an inner circumference of over a foot and a crater depth of some fifteen inches.

All photographs and drawings which accompany Prof. Jimenez's article on these formations are well worth looking at.  A copy may be seen in the club library.  It is interesting to note that the carbonate occurs as Calcite. The idea of geysers usually brings to mind hot solutions and under these conditions one would have expected the carbonate to have been deposited as aragonite.