Cave Features

Cave formations, called speleothems, are formed as acidic water dissolves small amounts of limestone rock as it flows through cracks or joints going into a cave. As the water comes in contact with the air of the cave, the carbon dioxide precipitates out. Once the carbon dioxide is gone, the water can no longer hold as much dissolved calcium; the excess calcium is precipitated on the cave walls and ceilings. Speleothems form very slowly, taking around 60 years to add 1.3 centimeters of material.

Speleothems can take many shapes; some formations found in caves include soda straws, stalactites, stalagmites, and columns.

Soda straws form as water seeps down from the surface and drops to the floor, leaving a tiny deposit of dissolved calcite on the ceiling. This deposit is in the shape of a ring and as more and more water droplets come through, the ring forms a small, hollow tube which hangs from the ceiling. This formation is called a soda straw.

Stalactites are formed from soda straws. This transformation occurs as water runs along the outside of the soda straw and deposits calcite on the outer surface. This causes the straw to become thicker and forms an icicle-like formation.

Stalagmites are formed as the calcite remaining in the water falling to the floor of the cave. Some of the calcite is forced out of the water by agitation as the droplet hits the floor.

Columns are formed when stalactites and stalagmites meet. They usually form under a single joint or crack.

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