Kind: captions
Language: en
If you go to Miami, like all of southern
Florida is sitting on top of fossil
coral reefs.
>> Oh,
>> the whole state of Florida has got coral
reef fossils underneath it. Anywhere you
go, you dig a hole
>> except the sink holes.
>> Well, the sink holes are holes in the
coral reefs.
>> Why would that exist?
>> It's Look, I was just in Florida three
months ago and I had the best sinkhole
experience.
>> That may be the first time that sentence
has ever been uttered on planet Earth
because Sinkhole experiences are
typically tragic.
>> Yeah. Well, I'm going to
>> Now we're going to talk about sinkholes
in Florida. All right. Oh, man.
>> So, the um bedrock of most of Florida is
limestone that's about 35 million years
old.
>> Wow.
>> So, it was deposited at the bottom of
the sea and there's a thick layer of
limestone. And when
>> what forms limestone?
>> Limestone or fossil reefs.
>> Oh, okay. They can they can be lots of
different things, but in Florida they're
fossil reefs. or coral heads and just
what you're talking about.
>> Right. So why why is the word lime in
there?
>> Cuz it's calcium carbonate and when you
bake calcium carbonate you get lime
which is used to make concrete,
>> right? And it's so it's a lime instead
of an old English word for this calcium.
>> Calcium, right? And we used and so um
lime stone
>> is calcium carbonate. Yeah.
>> And you um so it forms in ocean
situations can also form in fresh water
it turns out. But in ocean situations,
organisms build these reefs or just
layers of microorganisms that make
limestone. Like the cliffs of do for
instance. Oh yeah. Are a sort of non-
reef version of the reefs. But Florida
these reef ones and you can go to the
outcrops anywhere in Florida and you'll
see the coral sticking right out of the
rock. I mean it's it's like there it is.
It's just takes 35 million year old.
>> Yeah. Takes zero imagination to see it.
You're looking at the reef and
>> I used to live in Florida and I don't
ever remember seeing that. So
>> you don't look at the ground enough.
You're looking at the stars too much.
>> Yeah, I'm looking up.
>> So, so, um, I went to Florida because
I'm working on this fossil atlas of the
United States. And I had heard that
Florida had great fossils and I went to
University of Florida Gainesville where
they have a great museum. And I went out
with um to a limestone quarry where
they're quaring limestone to make
concrete and all this stuff. And we
first stopped at piles of the ground up
limestone. And I was looking around. I
found a beautiful fossil crab, like a
fossil stone crab that was like that
big.
>> And lots of chunks of snails and clams,
all the kind of things you see living
around a reef. But then here's the
kicker. That reef was 34 million years
ago. Over time, the earth goes up and
down depending on different things where
the continents are. So like the surface
goes up.
>> The surface goes up and down. And the
sea level is also going up and down. So
if you live near the coast, either the
sea level can go up and flood the land
>> or the land can go up and drain the sea
or both happen over time quite a bit.
>> So the limestone of the 34 million year
old limestone from Florida which used to
be under the sea
>> is now, you know, above the sea.
>> It's maybe 30 or 40 or 100 feet above
the sea. Limestone is dissolved by
rainwater, right? Because it's the
rainwater has got a little bit of
dissolved carbon dioxide in it which
makes it carbonic acid. when so
raindrops got kerning ice, it hits the
limestone and it dissolves a little bit.
So limestone get um forms caves.
>> Yeah.
>> That's where you find all the big caves
like like Mammoth Cave in Kentucky or
you know Carl's bad cavern in New
Mexico.
>> Wait a minute. Wait a minute. Wait a
minute. So Mammoth Cave is an old reef.
>> Yes.
>> In Kentucky,
>> dude.
Yes. Yes. Now you're getting it. You're
with me on this one. So, so you have
this landscape now that the rain is
making holes and these caves can get
huge. You've seen Mammoth caves.
>> Oh, yeah. I've been in a few caves. I
haven't been in Mammoth. Yeah. Yeah.
>> All of those caves are formed by
uplifted ancient God. Now, you mentioned
it. I was I was in this island in the
South Pacific in Cook Island. It's
Mangaya and it's an ancient
>> It's a coral island, full of caves.
>> Exactly. Right. So, but think about um
marine limestone that's been uplifted.
Think about the best analogy back to
food.
>> Yeah. is Swiss cheese.
>> Swiss cheese.
>> It's a block of cheese with holes in it
all over it. Right. So now what a
sinkhole is is when you put some weight
on the top of a part of the sinkhole
because when you lift it up and you
limestone has formed these holes in
there. They often fill up with ground
water. So it's like a Swiss cheese
that's full of liquid
>> and that gives a support as well.
>> Support. So, but the little say the top
of the sink hole is there and you park
your car on it and your car weighs
enough to crack the hole and suddenly
the whole thing collapses in on itself
and you have a round lake
>> and that's the thing is there they're
circular. That's
>> because they're round holes and they
become round legs. So So now you have
this thing that's there and um it's a
lake that's got steep walls on it
because you've collapsed in the side and
if you're a a turtle or an alligator,
you find your way in there and they fill
up with turtles and alligators are
living happily in there. If you're an
animal walking by and you like go for a
drink in the water or you fall in, you
can't get out because of the secret
walls. So, it become a trap.
>> Now, over time, dust and stuff fills it
up and the sinkhole fills up with mud
and bodies of all the animals that got
buried there. And northern Florida has
got I mean we went to this one limestone
quarry and you could see where they're
cut in the wall you could see
cross-sections of infilled sink holes
full of fossil mastadons and
rhinoceroses and giant ground sloths and
manatees and alligators and turtles and
so I'm like this is the coolest thing
I've ever seen.
>> Right. So it's a big cylinder.
>> It's a cylinder full of skeletons.
>> Jeez. And so and and the museum is
chocker block full of skeletons all of
them younger than the age of the
limestone 34 million years all the way
up to the ice age 2 million years ago.
>> Wow.
>> And we went digging. We went to this
other place called Montbrook. And you
give you a little knife to dig with and
I dug myself on. First I found um a
beautiful fossil turtle with a skull
intact and then I
>> So do you get to keep this stuff or
>> No, it goes to the museum there. Okay.
Like whenever I go I'm always like some
museum I'm working for. usually my
museum, but I'm always like this cool
stuff.
>> But is there like how does that work? If
there is there regulation around that
like Okay.
>> If you own the property, you own the
fossils.
>> Got it.
>> Which means that if you I mean, which is
a good argument to buy property.
>> Own a lot of fossils, right?
>> So, but I was This is a piece of
property that's owned by a private
citizen who is letting the University of
Florida dig there. They've been digging
for 10 years. They have from this one
little top of a little sinkhole
extracted something like I don't know
hundred different rhinoceroses.
>> And when I was there I dug on to a
rhinoceros.
>> Wow. Wow. So, I tell you, I left Florida
a changed person because I I've been
going down to Florida a lot looking at
fossils and things, but I had I didn't
really realize the Swiss cheese thing,
and there are thousands of those sink
holes, and they're all full of amazing
fossils. And as a result, Florida has
one of the best fossil records of early
mammals.
>> Wow.
>> In the country. If you want a fossil
mammal between the ages of 34 million
and now,
>> Yeah.
>> Florida and Nebraska are your two top
places.