Main Menu > Rocks and Mining > Water Recycles Rocks > Caves
A Subterranean Wonderland. Drop by drop,
year after year, cave deposits slowly grow. Because these formations build up
over many human lifetimes and are very fragile, they are irreplaceable. Today,
both federal and state laws protect cave deposits.
Stalactite
An icicle-shaped formation that grew down from a cave roof. Early in
their growth, stalactites resemble soda straws. |
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Flowstone
This special type of flowstone called drapery was deposited by water
flowing down a cave wall. |
Cave Popcorn
Formed on cave walls, the sides of other formations, and the
edges of pools. |
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Stalagmite
A pillar-shaped formation that grew up from a cave floor. The drip
and flow of water, along with the varying rate of growth, produced
this specimen's texture. |
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How to Make a Cave
Trickle rainwater through soil into cracks in a thick underground bed
of limestone. The water will absorb carbon dioxide from the air and
from microscopic organisms in the soil to become a weak acid.
H2O + CO2 = H2CO3
water + carbon dioxide = carbonic acid |
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Step 2
Let the acidic groundwater slowly dissolve calcite in the limestone.
Tiny cracks will grow bigger as more rock is dissolved.
H2CO3 + CaCO3 = Ca2+ + 2 HCO31-
carbonic acid + calcite = dissolved calcium + dissolved bicarbonate |
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Step 3
Continue this for thousands of years. The cracks will slowly
enlarge into underground tunnels. |
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Step 4
The acidic groundwater that creates caves can also build wonderful
cave formations. Loss of carbon dioxide from the water causes
calcite to crystallize.
Ca2+ + 2 HCO31- = CO2 + CaCO3 + H2O
dissolved calcium + dissolved bicarbonate = carbon dioxide + calcite + water |
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