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The Cave
Mr
K. McEachern and Mr J. Hutchesson and his sons Alan
& Bernie, first explored the cave in 1936.The original
entrance was a 17m vertical shaft, as visitor access
was restricted a stairwell had to be dug through the
limestone, this stairwell took Keith and Bunny 5 years
to dig. They developed the cave as a tourist attraction
with “Bunny" Hutchesson acting as the first permanent
guide, conducting tours from 4th January 1941. Since
1980, the cave has been part of the Lower Glenelg National
Park.
Formations
Most
limestone caves are formed by water seeping down through cracks and fault lines
in the limestone, dissolving the rock and creating fissures and tunnels. The
formation of Princess Margaret Rose Cave,
however, was assisted by water from the Glenelg River which worked its way
along a fault line for approx 500m. This occurred above its present height. The
water scalloped the walls of the cave and wore a reasonably level floor.
Rainwater,
as it seeps from the surface, acts as a weak acid to dissolve the limestone,
producing a solution of calcium bicarbonate. When this reaches the air of the
cave, carbon dioxide is released and calcium carbonate is deposited in the form
of calcite crystals.
These crystals make up the diverse and spectacular
formations of the cave.
The different colours are caused by tannins and
minerals washed down by rainwater from overlying soil.
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As the
solution drips from the cave roof, deposited carbonate is left adhering and a stalactite is formed. Straws or tubular stalactites are long, thin
hollow stalactites with a solution flowing
down inside the centre. |
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Solution
dripping from a stalactite builds a
stalagmite from the cave floor. If a
stalactite and stalagmite join they form a column and if that thickens it
becomes a pillar. Flow stone formations are caused by water
flowing over the walls leaving a smooth surface. Other formations at the roof
line are shawls,
blankets and bacons. The shapes and colours
of these narrow formations are accurately described by their names.
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Perhaps
the most unusual formations in the cave are the helictites.
Defying gravity,
these long, thin formations grow in all different directions. No one is certain
how they form, but the commonly accepted theory is that they begin on crystals
and are shaped by surface tensions and capillary action. |
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Other
mysterious formations in the Princess Margaret Rose Cave is the rarely seen cave coral, rimstone pools and sawtoothed shawls.
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