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| Floating rock piece, Rameswaram.vaishnava.in |
A
natural stone bridge,
interwoven
with the Hindu mythology - the Ram Setu Bridge – also known as
Adam's bridge is a long string of coral reef rocks that connects
the
Rameswaram
Island in Tamil Nadu, India to Mannar Island, off the north-western
coast of Sri
Lanka.
This bridge is believed to have been built across the sea for the
Hindu God Sri
Rama
by Hanuman and his associates when they marched across
a small strip of sea
to
Lanka to fight King Ravenna and bring back Seetha
(Sri
Rama's wife)
who was in siege.
In
the Sanskrit epic Ramayana,
it is mentioned that they jerrybuilt
a
passable
stone bridge across
the sea to cross over to the island country.
These
big fragments of reef rocks were exposed after the worst devastating
Tsunami that struck the eastern coast of India and other places on
December, 2004. These
huge coral reef rocks actually float in the water and never get
submerged because of lots of void spaces in them. It may
be
possible for humans to use these series of floating stones and
cross a huge water body.
At
Rameswaram I myself saw in some places huge stones weighing more
than 15 kg floating in big water tanks without getting submerged.
After
observation
first hand logical explanation is - invariably almost all the
floating stones are coral reef rocks made of calcium carbonate. They
have lots of very small hollow spaces once occupied by colonies of
tiny animals that
normally
build the reef in the
coastal marine
waters; most reefs were
built by stony corals
eons ago. Some newspaper articles report that such rocks are volcanic rocks and the floating rocks could be pumice. As far as Rameswaram and adjacent areas are concerned there are no outcrops of Volcanic rocks. Nor are there occurrence of Pumice. Pumice is of volcanic origin. Floating coral reef rocks are lightweight with skeletal remains of coral organisms or porous limestones that have become trapped with air, due to sliding in the continental shelf area. Further coral reef formations occur in the tropical areas in the inner and middle continental shelf. shelf. coral reef is an important part of an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate.
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| Volcanic pumice en.wikipedia.org |
Pumice is formed when superheated when highly pressurized rock is rapidly ejected from a volcano. The unusual foamy appearance of pumice is due simultaneous rapid cooling and depressurization, the latter creates bubbles by lowering the solubility of gases (including water and CO2) that are dissolved in the lava. This is akin to opening the carbonated water bottle, causing the gases to rapidly exsolve.
The
numerous small air cavities
in the rocks
are not even and are found to occur unevenly
inside them and also on the surface. Further, the weight of the
water displaced by them is more than their own weight. As
for buoyancy, the
following inference can be made:
Almost
all floating stones at
Rameswaram
are coral reef rocks with variable density and air cavities.
The
floating rock segment exposed to the viewer above
the surface has
more air cavities and less density.
On the other hand,
the bottom segment (immersed
in water)
has more density and less air
cavities.
Further,
it is likely, it may be due to salinity of the floating medium -
water.
No
matter how you drop the stone into
the water, it automatically realigns itself in such a way that less
denser
portion with more air cavities is turned towards the viewer.
K. N. Jayaraman (Author: navrangindia.blogspot.com)
