Stalactite facts for kids

Stalactite that is dripping water

A stalactite is a special rock formation that hangs down from the ceiling of a cave. Imagine an icicle, but made of stone! These amazing shapes are created very slowly, drop by drop, over many, many years.

When water drips from the cave ceiling, it often contains tiny bits of minerals, especially a mineral called calcite. As each drop hangs on the ceiling and then falls, a tiny amount of this mineral is left behind. Over time, these tiny bits build up, making the stalactite grow longer and thicker.

The rock formation that grows upwards from the cave floor, directly underneath a stalactite, is called a stalagmite. If a stalactite and a stalagmite keep growing towards each other for a very long time, they can eventually meet and join together. When this happens, they form a single, tall pillar known as a column.

How Stalactites Form

Stalactites are a type of cave formation called a speleothem. They are usually made of calcium carbonate, which comes from limestone. Here's how they grow:

• Water drips: Rainwater soaks through the ground and into the cave. As it travels, it picks up carbon dioxide from the soil and becomes slightly acidic.
• Dissolving rock: This slightly acidic water then flows through cracks in the limestone rock. It dissolves tiny bits of the limestone, picking up minerals like calcium carbonate.
• Mineral deposit: When this mineral-rich water reaches the cave ceiling, it hangs in a drop. As the water evaporates or releases its carbon dioxide, it can no longer hold all the dissolved minerals.
• Growth: A tiny amount of calcium carbonate is left behind. Each new drop adds another tiny layer, slowly building up the stalactite.

Different Types of Stalactites

Not all stalactites look the same! Their shape can depend on how the water drips and what minerals are present.

• Soda Straws: These are very thin, hollow tubes that look like drinking straws. They form when water drips very slowly from a single point.
• Conical Stalactites: These are the more common cone-shaped stalactites. They are wider at the top and get narrower towards the tip.
• Lava Stalactites: While most stalactites are found in limestone caves, some can form in lava tubes. These are created when molten lava drips and hardens.

Where to Find Stalactites

Stalactites are found in many caves around the world, especially those formed in limestone. Some famous caves known for their amazing stalactite formations include:

• The Caves of Nerja in Spain, which have huge columns.
• The Puerto Princesa Subterranean River National Park in the Philippines.
• The Choranche caves in France, famous for their "soda straw" stalactites.

These formations are very delicate and can take thousands of years to grow just a few centimeters. It's important to protect them when visiting caves.

Images for kids

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  Image showing the six most common speleothems with labels. Enlarge to view labels.

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  Demonstration of drip stone formation in a lab. The blue color is due to the addition of cupric ions (Cu2+) to the mother solution.

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  Pillars in the Caves of Nerja, Spain

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  Shark tooth stalactites

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  Ice stalactites on the gutter of a house

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  Ice stalactites on a frozen beach in Bete Grise, Michigan

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  Concrete stalactites

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  Calthemite soda straw stalactites under a concrete slab

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  Stalactites at the Puerto Princesa Underground River, Palawan, Philippines

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  Mineralized water drop forming at bottom of stalactites

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  Stalactites of the type called "soda straws" from the Choranche caves in the Vercors, France

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  Tubular lava stalactites

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  A tubular lava helictite

See also

In Spanish: Estalactita para niños