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Language: en
What separates the um fossilized plants
from I imagine everything doesn't get
fossilized, right?
>> Yeah. Yeah.
>> So, here's the key thing that you have
to know about fossils is that in order
to become a fossil, you've got to die.
>> Yeah.
>> And you got to get buried.
>> Okay.
>> Right. And if you don't get buried, say
you just fall over in the forest
somewhere, you're going to rot away.
>> So, it's death plus burial. So if you're
a dinosaur, you fall over and you die.
Chances are you're not going to become a
fossil unless you live in a place where
stuff gets buried. And what are those
places? They're places like Louisiana
for instance, right? If you Louisiana,
the whole landscape is sinking slowly
and the stream is always dumping out
sediment and putting more layers on it.
So an area that's sinking is what I call
dualorld or deposition world.
>> Right? And if you were to drill a hole
beneath New Orleans, you would go down
almost 20,000 ft in layered mud that's
only 25 million years old.
>> What?
>> That's literally miles of thickness.
Yes.
>> It's miles.
>> So if if a fish died in New Orleans
>> 10 million years ago, it would be 10,000
ft down.
>> Wow.
>> And in the sediment it was buried in is
being compacted into rock. So, I've seen
this p this image ge geologically of the
Gulf of Mexico and how it goes out
underwater and there's like this big
giant cliff. Yep. So, all of that stuff
is from the river.
>> Yeah.
>> Whoa.
>> Yeah. And from rivers dating back to
millions of years. So, the earth is as
it erodess mountain ranges, all the
sediment, groundup mountain ranges end
up at the edge of the continents and
piling up in thick layers of sediment or
limestone or other kinds of stuff. And
that's where you create the fossils. You
an animal dies or animal plant dies is
buried in an area that's sinking which
buries it deeply and that turns the
sediment into rock.
>> Yes.
>> And they're at depth. And then
eventually what happens is some other
first phenomenon pushes that area back
up.
>> So areas that were depositional areas or
DWorld,
>> right,
>> become lifted up into what is called
EWorld or erosion world. So if you can
look at North America for instance, most
of North America right now is erosion
world or E-World.
>> It's getting eroded away.
>> There's mountains. Anytime you see a
hill or a mountain, you know that
stuff's eroding away. Look at the
Mississippi River.
>> Anytime you see a river, right? River.
>> Exactly. Yeah.
>> In some areas. And so there are, think
about this. There are rivers in erosion
world like the Colorado River is cutting
the Grand Canyon. Not a good place to
become a fossil. That's just grinding
away and taking it out to the sea.
>> And it goes side to side and meanders
and Yeah. But that same river like
Mississippi when it gets down to New
Orleans, great place to make a fossil.
>> Ah,
>> so that's the Eorld D world difference.
And the best place to find fossils and
like maybe the best place in the world
to find fossils is western United States
because most of the last 500 million
years that landscape was sinking. It was
D.
>> But then when the uplift of the Rocky
Mountains started, it pushed that area
back up and exposed those rocks in
Eorld.
>> So you want D. So you bury them,
>> then lift them and erode the stuff off
the top of them and now they're exposed.
>> Exactly. And and sometimes you uplift
them in an irregular way. So in one
place you might be able to see a
cross-section of the entire stack.
>> Oh.
>> And there's a place near Cody, Wyoming,
where you can see from 2.5 billion years
to 60 million years in one spot.
>> Geez.
>> It's better than the Grand Canyon. That
is
And so because they've been lifted and
turned now it's it's it's more
horizontal or at an angle rather than
>> Yeah. Exactly. It used to be flat and
they turned up and they're almost
vertical and you just count the pages
like this all the way through.
>> Wow. And each layer has its
representative fossils.
>> Exactly. There like always there's sort
of local D world like the immediate area
around you. Like you're standing next to
a mud bluff and it it slumps down and
buries you. You just got buried in a
little narrowest piece of
>> D world.
>> I see.
>> But if you wanted to look at it at the
continental scale
>> there, most of North America is EWorld,
but they're little local ponds and
little local lakes. But those local
things are not going to get preserved.
They'll eventually fill up in a roadway
too.
>> So the fossils are going to be in those
places where the whole landscape is
sinking.
>> Whole landscape. So what places would
that be on Earth today? the edges of the
continents primarily or the shallow low
elevation parts of the margins of the
continents.
>> Okay. Is that generally true throughout
history?
>> Yeah. So, as a result, we really don't
have much of a fossil record for
mountains or hills.
>> Wow. So, so for example, right now,
humans are distributed primarily along
coastlines. So, so would it be the case
that land animals even though it's a
it's it's geographically limited, it's
still a good representation because uh
that's where most life is going to
concentrate anyway. Is is that fair?
>> It's true. That probably the case, but
like you know, you're still going to
miss the mountain goats and stuff like
that, right? Things that live only at
high elevations or, you know, even on
the Great Plains, some of those things
do get preserved. like the the animals
of the great plains were preserved
because the Rocky Mountains came up and
all the sediment coming off the Rocky
Mountains shed and buried things under
river sediments and then that area is
still coming up. So those river centers
are now being exposed.
>> Oh.
>> And so you have that kind of local
deorld um is a source of good fossils on
continents. And we found an amazing site
in Colorado in 2012 that was a lake on
top of a hill at 9,000 ft.
>> Wow.
>> And it filled up with
>> Lake Tahoe. No,
>> no. Was at Snow Mass Ski Area Snow Mass.
It's right 700 yards from the base of
the ski area. There's a little 12 acre
lake
>> that turned out to have been an ice age
lake
>> that filled up between 120,000 years ago
and 50,000 years ago. And we found 50
mastadons and 12 mammoths in this one
little lake in 70 days of digging.
>> It was an amazing thing. But that was a
a little tiny lake on top of a hill that
was a little temporary bit of deorld.
Yeah.
>> And in the future that'll erode away and
go away, but we got it before it eroded
away.
>> Wow.
>> Just our timing was very good.
>> Good timing. But but over geological
history, a lot of those are coming on
gone.
>> Yeah. Oh, yeah. Cuz that's at the top of
the hill. It's going to go,
>> right? It's going to go.
>> Hills go away. Mountains go away.
>> They're temporary.
>> Yeah. Never trust mountain ranges.
They're undependable. They rode away.
>> All right. All right. You can't depend
on them.
>> Yeah.