The Day the Dinosaurs Died Page #4

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Everything above the red line

that you see there is actually

material that used to be buried

that has been flipped up on end,

and is now... or flipped upside-down,

and is now laying as a pile

of broken-up material.

By studying the shape of the crater

and the upheaval of the rock layers,

Sean, Jo and the team can

compare this site to

the Yucatan impact zone,

Even a small asteroid strike like this

would have had dramatic consequences.

So it comes in at something like 26,000mph.

10km away from here, we would

have a fireball reaching,

maybe 20km away from here, a shock wave,

and, say, 40km away from here

are hurricane-force winds,

but that would just have been a bad day

in, today, northern Arizona.

So this is what a 50m-wide

asteroid can do -

it's devastating, but localized.

But what about an asteroid

that is nine miles across

and leaves a crater 120 miles wide?

To understand the effects of that impact,

the team needs to know exactly

how much energy it released.

To do that, they're comparing

rock samples from Yucatan

to data gathered from some of the

largest ever man-made explosions.

This is the Nevada Test Site,

the most bombed place in the world.

The US military have detonated

904 atomic bombs here.

To help us understand how atomic

bombs connect to asteroids,

we've enlisted the help

of physicists Mark Boslough

and David Dearborn.

The blast must have come

all the way through,

and I bet these windows blew out.

Those shards of glass would

be accelerated by 90mph wind.

- Wind, the windows were gone. Yes.

- And they're totally... boom.

This house was part of a test

village called Survival Town,

built to study the effects

of a nuclear blast.

It actually survived a blast

called Apple-2 in May 1965.

EXPLOSION:

WIND HOWLS:

Most of the damage is

done by the fireball...

and the heat that is generated,

or the blast wave as it goes by...

and the houses that were

in closer didn't survive.

Those of us who work on asteroid impacts,

we naturally started comparing

them to nuclear explosions.

It's a similar phenomenon.

The experimenters had high-speed cameras,

they had gauges that measured the

intensity of the shock wave,

the blast wave in the air.

The tests found that nuclear

explosions are devastating

even at a microscopic level,

causing catastrophic shock

to minerals such as quartz.

The pressure is so high in a shock

wave from a nuclear explosion

that it actually exceeds

the strength of a crystal.

Crystal is made up of a

uniform array of atoms

and that uniformity is completely

disrupted by a strong shock wave,

and that's what shocked quartz is.

In Bremen, Professor Joanna

Morgan is looking at quartz

found in rock cores from

the asteroid impact site.

From nuclear test data, she

knows exactly how much force

it takes to shock quartz.

From this, she can tell how

much force the Yucatan rock

has been subjected to and begin

to calculate the exact amount of

energy released when the asteroid struck.

So this is a piece of shocked

quartz that we recently drilled

from the Chicxulub impact crater.

There's lots of lines here.

Essentially, the more lines

we have on the screen,

different directions, the more

shocked this rock has been.

These are caused by the impact,

by the shock wave that travels

through this piece of quartz.

So we used exactly the same

hydro-codes, they're called,

to model nuclear explosions as we

do to model the impact craters.

We've actually stolen these codes

and applied them to our simulations

of impact crater formation.

What sort of force were

we actually talking about

from the asteroid hitting it?

This event was equivalent to

about 10 billion Hiroshimas,

so, absolutely enormous.

The most dramatic event in

the last 100 million years.

10 billion Hiroshimas combined?

- That's the amount of force

going into this? - Absolutely.

It's incredible, it really is.

Finally, we have hard evidence

of just how powerful the

asteroid strike really was.

10 billion Hiroshimas.

It's a major revelation.

But the truly incredible thing

about this asteroid strike

was that it changed the face

of our planet within seconds.

And now we know that,

we can do something that has

never been done before.

'Create a simulation of exactly

how the impact affected Earth

'and the dinosaurs.'

Here's what the new results tell us

about those crucial initial minutes

after the asteroid struck.

The asteroid, nine miles wide,

smashes into the Yucatan at 40,000mph...

vaporizing instantly.

The impact makes a hole in the earth

20 miles deep and 120 miles across,

turning the surrounding sea to steam

and shattering the earth below.

Rock from deep in the Earth's crust

then rises miles into the air,

forming a tower higher than the Himalayas

that collapses to form a strange

ring of peaks that exists today.

All this in the first ten minutes.

What did this mean for the dinosaurs?

Well, it started an unstoppable

and devastating chain of events.

First, like an enormous nuclear explosion,

a radiation fireball

10,000 degrees centigrade

spreads out from the impact zone.

This searing hot sphere

fries everything within

a 600-mile radius in an instant.

The truly global devastation had

its roots not in the blast,

but in the huge vapor plume

that rose out of the crater

and through the atmosphere.

A red-hot cloud of vaporized

asteroid and rock,

expanding upwards 600 miles,

spreading rapidly outwards to

fill the planet's atmosphere.

Back then, faraway New

Jersey was covered in ocean.

And it too would soon feel

the effects of the impact.

1,700 miles from the site of the impact,

the fireball wouldn't have been visible.

That blazing, towering, swirling cloud

would've been just over the horizon,

but we might have seen a faint glow.

The animals here were safe

from the direct radiation.

Two-and-a-half hours later,

like the sound of heavy

traffic in the distance,

the shock wave, now a sound wave, arrived.

Wind starts to whip up, growing

stronger and stronger until

we're facing into hurricane-force winds.

The blast wave from the impact

surged across the Earth at enormous speed.

Its effects would have been short-lived,

but those few traumatic hours

left an indelible impression in

the earth's geological record.

These are beads of molten rock

that rained down from the skies

and as they cool, they become glass.

And if you melt rock and you cool it fast,

it doesn't have a chance to turn

back into rock, it forms glass.

Glass called spherules.

And we find these little

spherules right here

in this mass death assemblage.

What produces the kind of

energy and heat needed

to form these spherules, then?

Well, when you have an asteroid impact,

it melts the rock and it flies

up through the atmosphere

and these bits of molten rock

rain down on the planet.

'These 66-million-year-old

droplets of molten rock show that

'debris was falling on landscapes

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