A formação de estalactites e estalagmites

Autor: 
John Fuller
Educational signs at Luray Caverns in Virginia, help to understand the difference between stalactites and stalagmites.
Alan Band / Fox Photos / Getty Images Educational signs at Luray Caverns in Virginia, help to understand the difference between stalactites and stalagmites

We refer the stalactite and stalagmite words the Greek word " stalassein ", which means" dripping ". It fit properly, it describes how the two are formed in nature. Although they look natural and somewhat frightening, the stalactites and stalagmites grow simply as a result of water passing over the inorganic material and through him.

The limestone caves, where most of the stalactites and stalagmites are found, are mainly composed of calcite , a common mineral found in sedimentary rocks. The molecules consist of calcite and calcium carbonate ions and are referred to as CaCO 3 , or calcium carbonate . When rainwater falls on a cave and runs through rocks, she carries carbon dioxide and minerals from limestone. If we mix water, carbon dioxide and calcium carbonate have the formula:

 

H 2 0 + CO 2 + CaCO 3 = Ca (HCO 3 ) 2

 

Ca (HCO 3 ) 2 is known as calcium bicarbonate and water carries the substance basically dissolved calcite through the cracks in the ceiling of a cave. However, once the water comes into contact with the air inside the cave, part of the calcium bicarbonate is transformed into calcium carbonate and calcite begins to form around the crack. As the water keeps dripping, the length and thickness of the calcite increases, giving rise finally a stalactite in the ceiling. The formation of stalactites can take a long time - usually grow around 6 mm and 25 mm per century.

The cross section of a cave full of stalactites and stalagmites.
Dorling Kindersley / Getty Images Cross section of a cave full of stalactites and stalagmites

 

Evidently, the stalagmites not simply emerge from the ground. The water that drips from the tip of a stalactite falls on the floor of a cave and deposit more calcite on a hill. Soon, you will see a stalagmite that resembles the shape of a cone. This is why you usually find stalactites and stalagmites in pairs and sometimes they grow together to form a large column. There are many limestone caves in the world, famous for its views drip, as the Carlsbad Caverns (New Mexico), the Timpanogos Caves (in Utah), the Mammoth cave (in Kentucky), and the Jenolan caves and Buchan (in Australia ).

There are some classic tricks to differentiate stalactites from stalagmites.

  • Stalactites cling "firm" to the top of the cave.
  • Stalactite has a "t" as in "top".
  • Stalactite has a "c" as in "coverage."
  • Stalagmite has a "g" as in "grass", lying on the floor.

Stalactites and stalagmites

You may not know but you may have some pieces of stalactites or stalagmites in your own home. The contractors generally use lime and other mineral deposits found in caves for the construction of houses. Alabaster, a deposit found in stalactites and stalagmites, is a decorative stone that can be used in fireplaces, table tops, light fixtures, sinks, bowls and vases.

For more information on caves and cave exploration is everything, see next page.