Cavern Classroom: Prehistoric Era
Scientists
believe nature began to slowly craft Howe Caverns some six
million years ago - long before even the ancient, extinct
animal known as the woolly mammoth appeared on Earth. The
caverns are unique for more than their age and beauty -
they are among a very small number of mineral caves in the
world.
In those long-ago, early days, the eastern
part of New York State was covered by an arm of the Atlantic
Ocean. The waters of this sea swarmed with life: corals,
sponges and many creatures similar to oysters, clams and
snails were all plentiful. Many of these creatures built
their shells from calcium carbonate, which they gathered
from the waters around them. Generation after generation
of these creatures lived and died in their watery home.
And - very slowly - the bottom of the sea became covered
with hundreds of feet of the creatures' empty shells and
fine particles of dirt.
At first, these deposits were very soft. But
as layer upon layer of new deposits fell to the sea bottom,
the pressure built up. Finally, the lower layers were pressed
into a type of rock called limestone.
Millions more years passed, and the continent
of North America began to rise slowly out of the sea. This
was during the Cretaceous period of Earth's early history,
some 65-136 million years ago. As the sea water drained
from the rising mass of rock, a brave new land began to
form.
Hence, the beginning of a remarkable era.
Rain fell gently upon the new land. While much of this rain
water drained away in brooks and rivers, a great deal of
it soaked into the ground, just as it does today during
a cloudburst.
Most people think of water as a very "soft"
substance: you can plunge your hand into a tub filled with
water, and it won't really hurt (If you try the same thing
with a tubful of rocks, on the other hand, it will hurt.).
But as soft as water seems, its motion and movement - no
matter how slow - can have a powerful effect on even very
hard rocks over a long period of time.
Because the limestone beds laid down by the
sea creatures were softer than many rock formations (such
as marble or granite), the rain water trickling down from
the ground above soon began to erode the top layers. Small
cracks opened up to the layers below, and the rain water
dissolved its way through them, too. In time, the small
cracks grew to be large cracks through which underground
streams flowed. And that is how the great cave formations
and winding passageways of Howe Caverns were formed: over
the course of millions of years, underground brooks and
streams gently carved them out of the solid limestone deposits
left behind by sea creatures eons before.
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Learn
More About Howe Caverns In Our Cavern Classroom:
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