Karst

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Karst
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Karst in Slovenia
The Classical Karst or the Kras Plateau, is a
limestone plateau region in southwestern Slovenia
extending into northeastern Italy
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Karst in Slovenia
The region is famous as the inspiration for the
geological term karst topography
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Karst Topography
Karst topography is a landscape shaped by the
dissolution of soluble bedrock Most typically
when carbonate rock such as limestone or
dolomite, is dissolved away by mildly acidic rain
and ground water
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Karst Topography
As rain falls through the atmosphere, or when
water percolates through soil, it can easily pick
up CO2, which dissolves in the water forming
carbonic acid H2O CO2 gt H2CO3
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Karst Topography
This mildly acidic water begins to dissolve the
surface of fractures or bedding planes in the
carbonate (limestone) bedrock Over time these
fractures enlarge as the bedrock continues to
dissolve
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Karst Topography
Many karst regions display distinctive surface
features, such as sinkholes, pinnacles and
pavement Due to subterranean drainage, there
may be very limited surface water
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Karst Topography
Karst topography is also commonly characterized
by caves, sinkholes and streams that disappear
and reappear
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Caves
Over time, underground water can create cave
passages and large rooms (Mike will discuss caves)
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Rock Shelters
Note that many rock shelters, such as the Canyon
del Muerto Mummy Cave, Arizona, are not formed in
karst, but rather are the results of collapse
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Pollution and Karst
Karst terrain is very subject to pollution
because the sinkholes, sinking streams and caves
can easily funnel the pollution down to the water
table
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Pinnacle Karst
Even on a small scale, karst landscapes can be
very impressive
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Tower Karst
On a grand scale, karst terrain can be extremely
spectacular, such as the tower karst found in
Guangxi, China
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Tower Karst
Such tower karst has served as inspiration for
the distinctive art from Southeast Asia that
commonly depicts a seemingly magical landscape of
magnificent rock pillars that rise above valley
floors and utterly dwarfs any manmade features
that may appear in the work
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Phang Nga Bay, Thailand
Phang Nga Bay is a beach resort and national
park, which is world famous for its tower karst
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Phang Nga Bay, Thailand
Limestone karst and the sea mix well
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Sinkholes
Sinkholes are perhaps the most common surface
expression of karst The Central Kentucky Karst is
a prime example
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Sinkholes
Note the absolute lack of surface streams If the
sinkhole is deep enough, the water table may be
exposed
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Sinkholes
Sinkholes can also intersect cave passages
Rio Camuy Cave, Puerto Rico
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Sinkholes
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Sinkholes
Over pumping of ground water in Antelope Valley,
California caused fissure and sinkhole
depressions on the Rodgers Dry Lake bed, which is
composed of gypsum and other salts
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Winter Park Sinkhole, Florida
On 8-9 May 1981, during a drought in Central
Florida, a massive collapse sinkhole formed in
Winter Park, Florida
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Winter Park Sinkhole, Florida
In a single day, the hole widened to 320 feet and
to a depth of 90 feet, destroying an car
dealership, a public pool and "ate" an entire
two-story home
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Sinkholes
Such catastrophic collapses can occur when the
water table drops
Without the buoyant effect of the water, the
overburden of rock (ceiling) caves-in
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Giant Daisetta, Texas Sinkhole
A sinkhole appeared on Wednesday, May 7, 2008 in
Daisetta, Texas northeast of Houston By the next
day it was 100 feet deep and 600 feet wide
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Giant Daisetta, Texas Sinkhole
Two days later, the sinkhole had grown to be 260
feet deep and 900 feet wide It had swallowed oil
tanks, trees, tractors and other vehicles The
mixture of oil and mud at the bottom of the
sinkhole made it look like a tar pit
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Giant Daisetta, Texas Sinkhole
The sinkhole lies on top of a salt dome It is
believed that water had seeped into the top of
the dome and had dissolved away salt leaving a
void Also, oil was being pumped out of the salt
dome and this may have helped create a void
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