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Karst is a term
geologists use to describe a landscape that is principally
formed by the dissolving of bedrock and is characterized
by caves, sinkholes, springs, and underground streams.
Karst is a hollow terrain much like a piece of Swiss
cheese coated with a thin layer of soil. These interconnected
cavities can range in size from tiny cracks to stadium
sized rooms.
Karst
Is Invisible
Protecting karst presents many challenges, but the primary
problem in karst conservation is that karst can’t
be seen from the surface. Most definitions of karst
include a list of surface characteristics: sinkholes,
disappearing streams, cave entrances, and large springs.
While these are indeed indicators of karst regions,
they are only surface expressions of the underground
landscape. These surface characteristics hint at the
vast systems of interconnected cracks, crevices, and
conduits that lie below the ground. It’s difficult
to convey the importance of protecting something that
can’t readily be seen. People view the forests
or the mountains and recognize the beauty and value
that these landscapes contain, but most people will
never see the underground landscape – the subterranean
streams, rivers, waterfalls, underground lakes, and
canyons – and therefore cannot appreciate the
conservation values of these features.
Ichetucknee Springs, a series of
springs discharging 233 million gallons of crystal clear
water a day, supply entirely all of the water for the
Ichetucknee River in Central Florida. Much of the flow
of the Ichetucknee Springs group may be water from Alligator
Lake, Clay Hole Creek and Rose Creek. The flow of both
creeks disappears into sinkholes 9 miles north of the
springs and has been dye traced to the Ichetucknee.
In ancient times, the river once flowed over the land,
but as it cut down into the limestone, it was pirated
underground. Though this part of the river is hidden
from view, improper land use above it can still have
a direct effect on the river below. The spring group
and much of the river are protected by the State of
Florida, but the entire river is only partly protected.
Though the underground portion of the river cannot be
seen, protecting the watershed above this hidden river
is just as important for the overall health of the river
system.
Karst
Terrain Is Hollow
Karst is truly a 3-D landscape and the most common misunderstanding
by people living in karst regions is that the bedrock
is solid without voids. Most people have no clue that
the ground they stand on is actually hollow. Some residents
may know of a local cave or some may have heard about
sinkholes in the area, but they are unaware of the true
extent of the voids, cavities, and cave systems that
have formed below the surface. Most people are unaware
that they may be living on top of a huge cave chamber
or that an underground river may run beneath their property.
Many Caves Remain Undiscovered
Many cave entrances are either inaccessible by man or
have yet to be found. Most of the obvious cave entrances
were discovered over time, but many new cave systems
are dug open every year. The entrance to Scott Hollow
Cave in West Virginia was dug open in 1984. Prior to
the digging there was no natural entrance. After studying
the local geology, the discoverers determined that there
should be a cave in the area and they located the most
likely area to dig. They eventually dug into a vast
cave system that has been explored to over 30 miles
in length. The cave contains a large underground river
that flows 400 feet beneath the surface and is the main
drainage for the dry valley above.
Alabama has significant karst regions, primarily in
the northeast corner of the state, and over 3,400 caves
have been documented. It’s estimated that the
potential number of caves could be upwards of 40,000,
so less than ten percent of all the potential caves
have been found. Most of these cave systems will never
be found, but they still exist and play an important
role in the connection between the surface and the subsurface. |
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What is Karst?
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