Limestone is a sedimentary rock formed from compressed organic material that is often found underwater. Limestone caves are formed through erosion as acid rain dissolves the limestone rock, creating cracks and underground streams. Stalactites form on cave ceilings as mineral-laden water deposits calcium carbonate in thin rings, eventually hanging down. Stalagmites form on the floor below as water drops from stalactites deposit more calcium carbonate upwards over time. The world's most decorated cave is Lechuguilla Cave in New Mexico.

1. Limestone Caves Report
Limestone is a sedimentary rock often found at the bottom of the sea. It is naturally formed
by the compression of dead and decayed organic material. Limestone caves are caves
which are formed by erosion. They are believed to be the deepest and largest found by man.
The carbon dioxide released by animals reacts with the water droplets present in the clouds
and turns into dilute Carbonic acid (CO2 + H2O -> H2CO3). This acid falls on the Limestone
(Calcium Carbonate) and has the capability to dissolve it into salt and water and releases
carbon dioxide in the process (2H2CO3 + 2CaCO3 -> CaCO3 + CO2 + H2O) (One of the
unique properties of Limestone is that it can dissolve in a weak acidic solution when
compared to other rock types). This in turn causes crack to form on limestone. The rainwater
percolates through eventually forming underground streams or large caves.
Stalactites are the formations that form on the
ceilings of caves, which looks a lot like icicles.
Formation of stalactite begins when a single mineral
laden drop of water, i.e. the acidic water chemically
combined with carbon dioxide, calcium carbonate
and calcite [H2CO3 + CaCO3 -> Ca(HCO3)2]. The
water drop squeezes between the rocks and drops to
the floor of the cave leaving behind a small deposit of
the dissolved calcite in the shape of a thin ring. Each
subsequent drop that forms and falls deposit another
calcite-ring. Eventually, these rings form a very narrow hollow tube hangs from the ceiling is
commonly known as a ‘Soda Straw’ stalactite. Soda Straws can grow quite long, but they are
extremely fragile. If they become plugged by debris, water begins flowing over outside,
depositing more calcite and creating the more familiar cone-shaped stalactite.
The water drops that fall from the tip of the
Stalactite, deposit more calcite on the floor
below, eventually resulting in a rounded or
cone shaped stalagmite. Stalagmites are the
formations found on the floor of caves,
reaching upward to touch the stalactites
hanging above from the ceiling. Unlike
stalactites, Stalagmites are rounder, smoother
and has no central tube. Straight formations of
stalactite and stalagmites can meet and fuse to
create column.
Limestone can be found anywhere in the world. They are more often found in rocky regions.
The world's most spectacularly decorated cave is generally regarded to be Lechuguilla Cave
in New Mexico. Lechuguilla and nearby Carlsbad Cavern are now believed to be examples
of another type of solutional cave. The largest Pseudo limestone cave is on Jeju Island.
There are several caves in the Andaman and Nicobar Islands in India.