Where Are Stalactites Formed?
Stalactites are the stony deposits hanging like icicles from the roofs of caves. Stalagmites are similar deposits rising in columns and cones from the caves’ floors. Caves occur chiefly in limestone and chalk formations, because water dissolves these rocks.
The River Lesse, for example, in its passage through the caves of Han, in Belgium, has been estimated to dissolve some five tons of limestone in a day. It is redeposited as carbonate which builds up the stalactites and stalagmites. The seepage of water down the cave walls and through the roof produces constant dripping and evaporation.
Stone icicles form on the cave roof, slowly growing with the addition of successive layers of calcium carbonate. The word “stalactite” comes from the Greek and means “drop by drop”. There is, too, a general term “dripstone” which is used to cover all formations.
Stalactites are at first hollow, for the depositing of the carbonate is fastest at the outer ring of the water drop. As the evaporating water deposits its mineral matter, the cavity slowly fills up and the stalactite becomes solid.
When water trickles out
of a narrow cleft in the roof, instead of a small hole, a hanging curtain of
stone will form in place of a conical stalactite. The Jeita Grotto in Lebanon
is home to the world’s largest stalactite (26.9 feet or 8.2 meters).
If the water flows so quickly that it splashes on the floor of the cave, it deposits its calcium carbonate there and small cones and domes of stone called stalagmites begin to rise. These may grow up to join the stalactites above and form single columns. Some cave floors are covered with stalagmites. They may grow so high that they block the cave entrance.
One of the tallest known stalagmites, one measuring about 98 feet high, is located in the Cévennes National Park, in Lozère, France, in the Aren Armand cave. Other one is 62.2 metres (204 ft) high and is located in the cave of Cueva Martin Infierno, Cuba.