|
To
the
south
of
the
mainland
of
Florida
is
the
skeleton
of
an
ancient
and
a
not-so-ancient
coral
reef.
Generally,
only
the
parts
above
the
water
are
thought
of
as
the
Florida
Keys,
but
the
entire
platform
evolved
while
under
water.
There
are
about
882
charted
islands
beginning
with
Miami
Beach.
These
islands
were
referred
to
as
"cayos"
by
the
early
Spanish
travelers
and
map
makers.
The
English
generally
used
the
word
"kay"
or
"cay"
for
small
islands.
Somehow
this
became
"Key"
for
us
Americans.
The
first
specific
written
use
of
"key"
being
used
for
our
islands
that
I
have
is
lawsuit
for
a
shipwreck
in
1744
which
was
before
the
Revolution.
There
is
probably
more
to
the
derivation
than
this.
The
Florida
Keys
can
be
categorized
based
on
their
geology.
The
upper-Upper
Keys
or
northern
Keys
(Miami-Dade
County)
are
sedimentary
in
nature.
These
begin
at
the
northern
boundary
with
Virginia
Key
and
pass
southwestward
to
about
Soldier
Key
and
are
generally
sediments
on
top
of
a
foundation
of
a
more
solid
layer
of
rock.
The
surfaces
of
these
islands
are
not
rock-hard
as
the
remainder
of
the
Keys.
From
Soldier
Key
southward
are
the
non
sedimentary
Keys
classified
as
High
Coral
Keys,
Low
Coral
Keys
and
the
Oolite
Keys.
There
is
not
a
clear
dividing
line
but
the
Upper
and
Middle
Keys
are
of
Key
Largo
Limestone
which
are
the
peaks
of
once
live
coral
forests.
These
were
once
live,
thriving
and
dense
forests
of
many
corals
and
other
marine
organisms
-
flora
and
fauna.
As
one
would
expect
the
coral
forests
were
of
various
densities
and
heights;
however,
they
are
of
less
height
the
farther
south
one
goes
except
for
Key
West.
These
have
heights
from
10
to
18
feet.
The
Low
Coral
Keys
are
from
five
to
10
feet.
As
the
glaciers
reformed
taking
water
from
the
ocean,
sea
level
dropped,
the
coral
forests
died
and
collapsed
into
islands
we
now
live
on.
The
Lower
Keys
was
a
huge
shallow
sandy
and
oolite
shoal
traversed
with
many
channels.
Oolite
is
compacted
small
egg
shaped
deposits
of
calcium
carbonate
and
in
this
area
lays
on
top
of
Key
Largo
Limestone.
Big
Pine
Key
signals
the
beginning
of
the
Oolite
Keys.
Human
history
begins
with
geography
and
migration.
Geography
defines
possible
physical
places
to
live,
and
we
migrate
to
the
geographic
locations
that
serve
our
needs.
Many
geographic
locations
are
the
result
of
internal
upheavals
of
the
earth's
crust,
or
lack
thereof.
The
newer
geological
structures
of
the
Florida
Keys,
however,
were
created
by
marine
life.
I
do
not
believe
we
know
the
complete
process,
but
it
is
said
that
there
was
an
ancient
reef
about
500
million
years
ago.
During
the
Pleistocene
Epoch
(2-3
million
years
ago)
shifting
sands
formed
massive
shoals
over
the
ancient
geologic
ocean
bottom.
The
tops
of
these
sand
shoals
were
shallow
enough
for
photosynthesis
from
sunlight
to
allow
corals
to
grow.
Corals
do
not
significant
grow
is
waters
deeper
than
40
feet
-
there
is
not
enough
sun
light.
The
"corals"
are
carnivorous
animals
with
hard
skeletons
that
eat
other
small
organisms.
Actually,
the
coral
animal
is
called
the
"polyp"
and
its
outer
skeleton
is
"coral."
It
is
of
the
phylum
Coelenterata
(hollow
sac)
and
the
class
Anthozoa
(flower
animal).
These
coral
polyp
growths
formed
on
top
of
the
sandy
shoals.
If
conditions
are
right,
corals
can
grow
forests
under
water
just
as
trees
do
on
land.
As
they
die
the
calcium
carbonate
skeletons
accumulate
as
do
leaves
and
branches
of
forests.
Unlike
trees
whose
leaves
and
branches
are
organic
and
decay
(rot),
the
skeletons
of
the
corals
remain
and
form
piles
which
when
large
enough
become
an
island.
At
that
time
the
water
level
is
estimated
to
have
been
about
20
or
more
feet
higher
than
it
is
now.
This
was
the
beginning
of
the
not-so-ancient
(today's)
coral
reef;
albeit,
under
water.
Principal
reef
building
corals
were
the
elk
horn,
stag
horn,
brain
and
star
corals.
They
were
the
architects
and
builders.
The
spaces
in
between
these
large
corals
were
filled
in
by
many
other
calcium
carbonate
organisms
and
plants.
These
include
sea
fans,
mollusks,
corals
debris,
et
cetera;
however,
the
most
prolific
is
a
relatively
unnoticeable
green
algae
called
"Halimeda."
The
entire
mass
is
solidified
and
cemented
together
by
the
many
calcium
carbonate
precipitates.
There
are
a
host
of
other
organic
and
inorganic
calcium
carbonate
sources,
including
the
sea
water
itself.
Therefore,
the
deepest
layer
was
the
ancient
ocean
bottom
with
layers
of
sand
on
top
of
it
and
a
new
coral
reef
building
layer
by
layer
on
top
of
that.
For
some
unexplained
reason,
about
100,000
years
ago
the
earth's
temperature
began
cooling
and
the
two
polar
ice
caps
began
to
grow.
The
increased
ice
in
the
polar
caps
very
slowly
removed
fresh
water
from
the
oceans.
As
a
result,
the
ocean
level
dropped,
the
living
reefs
began
to
die,
and,
with
time,
became
completely
exposed
-
Voilia,
the
Keys.
As
the
sea
waters
fell,
the
shoreline
moved
outward
and
more
land
mass
was
exposed.
The
ocean
level
is
thought
to
have
fallen
as
much
as
250
to
300
feet
at
its
lowest
levels.
Florida's
coastline,
and
especially
the
gulf
coastline,
would
have
extended
outward
many
miles
from
the
present
coastline.
One
could
have
walked
to
the
outer
reefs
and
even
to
the
Dry
Tortugas
area.
Most
of
the
Keys
may
even
have
been
connected
together.
The
Everglades
became
a
vast
savanna
with
animals
such
as
the
camel,
bison
and
mammoth.
As
nature's
pendulum
swung,
about
30,000
years
ago
the
polar
caps
slowly
began
to
melt
and
the
sea
water
began
to
rise.
With
the
passing
of
time,
the
coral
crust
was
again
covered
with
water.
As
the
sea
level
rose,
it
spilled
over
the
outer
reef
from
the
east
and
filled
today's
Hawk
Channel.
Florida
Bay
was
flooded
by
the
Gulf
from
the
west.
New
coral
began
to
grow
where
conditions
were
right.
Strong
water
currents
of
tidal
and
storm
actions
washed
back
and
forth
cutting
channels
at
lower
passages.
The
colder,
saltier
and
nutrient-richer
Florida
Bay
water
flowed
through
and
impeded
new
coral
growth
wherever
it
touched
the
live
corals.
Geologists
and
oceanolgists
that
I
have
spoken
with
estimate
that
the
higher
points
of
the
Keys
(Solares
Hill,
Lignum
vitae
Key,
and
Windley
Key)
probably
were
exposed
to
air
about
50,000
years
ago.
Because
the
Upper
Keys
were
higher
and
generally
longer
than
the
Lower
Keys,
there
were
fewer
channels
for
water
to
flow
through
and
impede
coral
growth.
That
is
the
reason
there
are
more
outer
reefs
in
the
Upper
Keys.
This
effect
can
be
easily
seen
on
a
map.
The
flow
was
so
significant
that
the
Lower
Keys
are
aligned
more
north
and
south
than
the
Upper
Keys.
It
was
so
killing
that
very
little
coral
has
grown
west
of
Key
West
in
the
last
6,000
years.
The
fossilized
layer
of
this
coral
growth
is
known
as
Key
Largo
Limestone,
a
name
given
by
geologists
for
this
type
of
limestone
formation.
The
Upper
and
Middle
Keys
are
primarily
of
Key
Largo
Limestone
although
it
lays
below
the
oolitic
formations
to
the
north
and
south.
Coral
rock
is
a
generalized
word
to
define
the
aggregate
of
the
"corals"
and
all
of
the
other
calcium
carbonate-producing
organisms.
Splendid
examples
can
be
seen
at
the
walls
of
the
Marvin
D.
Adams
Waterway,
or
the
Windley
Key
Quarry
(see
photo).
The
Lower
Keys
and
Miami-Dade
area
are
of
oolite
(both
are
called
Miami
Oolite).
Below
the
oolite
is
Key
Largo
Limestone.
As
time
passed,
well
defined
islands
evolved
and
mature
botanical
growth
flourished.
The
water
levels
continued
to
rise
and
formed
and
reformed
channels.
Wind,
birds
and
water
carried
in
botanical
life
that
slowly
took
root
and
grew.
These
plants
and
newly
arrived
animal
life
lived
their
life
cycles
on
the
islands.
Rich
soil
was
formed
from
the
decayed
organic
material.
Hurricanes,
fires
(organic
soil
will
burn)
and
clearing
by
settlers,
including
us,
have
considerably
thinned
the
once
rich
soil.
Some
original
soil
has
been
covered
by
fill
obtained
by
dredging
of
canals
that
makes
it
appear
even
less
evident.
North
American
Indians,
and
possibly
other
native
groups,
migrated
to
these
fertile
islands.
The
islands
are
peppered
with
habitation
midden
sites
waiting
to
be
scientifically
studied.
A
huge
mound
of
coral
rock,
known
locally
as
the
Key
Largo
Temple
Mound,
and
a
burial
mound
on
Lignumvitae
Key
beckon
credentialed
archaeologists
to
reveal
their
history.
Geologists
are
certain
that
as
the
polar
ice
melted,
Hawk
Channel
changed
from
dry
or
damp
land
to
swamp
land
and
finally
as
it
is
today.
Florida
Bay
was
the
Everglades
of
yesteryear
and
the
Everglades
area
was
a
savanna.
This
means
that
early
Paleo-Indians
could
have
walked
or
waded
out
to
the
present
reef
some
six
to
seven
thousand
years
ago.
If
so,
these
early
Paleo,
or
Archaic,
Indian
village
sites
that
might
have
existed
are
now
under
water.
In
November
2002,
Mel
Fisher
under-water
archaeologists
found
an
underwater
forest
near
the
site
of
of
the
Henrietta
Maria
slave
ship
about
35
miles
off
of
Key
West.
It
appears
to
be
a
burned
forest
of
prehistoric
pine
land
and
radiocarbon
cones
and
wood
were
dated
as
8,400
years
old.
Albeit
no
human
remains
have
been
found,
it
does
indicate
that
a
habitat
was
available
had
humans
been
there.
I
predict
more
evidence
will
be
discovered
where
there
is
sand
to
cover
the
artifacts.
As
a
comparison
date,
this
would
have
been
some
3,000
years
before
the
earliest
Mesopotamian
Cities
that
have
been
carbon
test
dated.
Going
back
to
the
formation
of
soil,
it
was
evidently
very
good.
The
type
of
vegetation
also
had
to
be
of
the
type
that
could
anchor
itself
to
withstand
the
wind
and
water.
So
prolific
and
mature
were
the
trees
that
the
Keys
served
as
an
important
source
for
lumber
in
the
early
times.
James
Grant,
the
first
English
governor
of
East
Florida,
sent
Captain
Benjamin
Barton
to
the
Keys
in
1763
to
stop
Bahamians
from
cutting
large
quantities
of
mahogany
and
other
valuable
timber.
As
late
as
1849,
U.S.
Coast
and
Geodetic
Surveyor
F.
H.
Gerdes
stated
in
his
report
on
Key
Largo:
"At
the
lower
pt.
of
Whalton's
Cove
or
about
7
miles
from
the
upper
pt.
of
the
Id.
[island]
is
an
elevation,
named
Basin
Hill,
90
ft.
high,
according
to
Capt.
Barnet
and
Blunt's
chart.
"
We
know
that
the
surface
elevation
is
about
15
feet
there
today.
Gerdes
went
on
to
explain
that
he
also
thought
the
90
feet
included
the
trees
as
"the
elevation
does
not
appear
to
be
near
90
ft."
One
of
the
Keys
north
of
Ocean
Reef
is
named
"Palo
Alto"
which
could
be
translated
as
"tall
wood."
In
historical
times
the
outer
and
patch
reefs
have
been
growing
upward,
almost
keeping
pace
with
the
rise
in
sea
water.
As
previously
stated,
outer
reef
growth
is
especially
evident
in
front
of
the
longer
Upper
Keys,
which
have
held
back
the
coral-killing
currents
of
Florida
Bay.
None
of
these
changes
in
sea
level
happened
rapidly.
In
geologic
time,
1,000
years
is
just
a
blink
of
the
eye.
Sea
level
is
not
static;
it
has
been
rising
and
falling
since
the
beginning
of
time.
For
example,
three
recent
sea
level
peak
heights
were
about
120,000,
80,000
and
30,000
years
ago.
The
one
that
completely
covered
the
Keys
sand
shoals
well
enough
for
significant
coral
growth
on
their
highest
points
was
120,000
years
ago.
The
navy
had
been
recording
specific
tide
and
sea
levels
at
Key
West
for
decades.
Using
that
data
as
a
reference,
some
experts
believe
that
the
sea
level
has
been
rising
an
average
of
about
2
feet
every
1,000
years.
Almost
all
agree
that
it
has
been
rising,
but
others
believe
that
the
rate
of
rise
has
been
less.
This
generally
is
thought
to
be
caused
by
global
warming
due
to
a
decrease
in
the
ozone
layer.
Instead
of
the
8,000-year
average
of
3.5
inches
per
100
years,
in
1989
it
was
reported
to
be
15
inches
per
100
years
at
Key
West.
Will
the
future
ocean
begin
to
fall
again,
or
will
the
pendulum
keep
swinging
and
raise
the
water
another
20
feet
to
inundate
south
Florida
up
to
about
Sebring
in
central
Florida?
At
this
rate
and
without
other
changes,
in
about
1,300
years
the
water
will
have
risen
about
16
feet
(5
meters).
Only
one
small
point
in
Key
West,
Lignumvitae
Key,
Windley
Key
and
a
ridge
on
Key
Largo
and
Plantation
Key
will
remain
dry
at
high
tides.
An
argument
against
this
extreme
is
that
there
have
been
smaller
undulations
of
sea
level
since
the
large
one
about
30,000
years
ago.
These
are
estimated
at
8,000
to
6,700;
4,300
to
3,400;
2,800
to
2,000
and
1,600
to
1,200
years
before
present.
The
argument
for
an
extreme
increase
is
the
effect
of
man
and
the
ozone
layer
called
global
warming.
Sources:
Land
from
the
Sea
by
John
Edward
Hoffmeister,
1974;
Geology
of
the
Florida
Keys
by
Eugene
A.
Shinn,
Oceanus,
1988
and
Paleoshorelines,
Reefs,
and
a
Rising
Sea:
South
Florida,
U.S.A.
by
Barbara
H.
Lidz
and
Eugene
A.
Shinn,
1990.
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