In the winter of 1807,
a lone fur-trapper journeyed deep into
the heart of the Rocky Mountains.
Somewhere near the headwaters of the Yellowstone River
he found a lost world.
ruled by ice, fire and brimstone.
A world of extremes that challenges all that strive to live here.
A place that has become perhaps the most treasured wilderness on Earth.
Winter in Yellowstone.
Minus 40 degrees.
零下 40 度
Fahrenheit or centigrade, it doesn't really matter,
at minus 40 the two scales read the same.
For half the year, Yellowstone is frozen solid.
Yet in the middle of this ice world there is scalding heat.
This is no ordinary place and this is no ordinary winter.
The fate of everything here lies in the hands of forces
of almost unimaginable power.
Yellowstone is deep in the heart of the Rocky Mountains of North America.
An isolated high plateau defended by rugged peaks.
And its location is what makes it so different.
Right beneath Yellowstone a unique quirk of geology
means that molten rock
from deep in the earth comes unusually close to the frozen surface.
No one knows why it happens right here,
but its impact is what has made Yellowstone world famous.
Yellowstone is the most extensive geothermal area on Earth.
It has over 10,000 thermal wonders
and more geysers than the rest of the world put together.
Old Faithful is Yellowstone's most well-known geyser.
It shoots 5,000 gallons of water
几乎每隔一个小时 它就往空中喷出5000 加仑水
150 feet into the air almost every hour.
But the forces that fuel this spectacular display
have an influence far greater than we can see on the surface.
Paradoxically, it's all this underground heat
that helps make the Yellowstone winter
one of the coldest and toughest in America.
It's November and winter is beginning to take hold.
As it gets colder, one animal here gets stronger.
Wolves. The winter is their time.
Gradually, it weakens their prey.
This is the Druid wolf pack,
one of the largest and most powerful in Yellowstone.
The pack have this bull elk surrounded.
But there's a problem.
The pack won't follow the bull into the river.
They won't risk freezing to death in the ice cold water.
What's more, now the elk's antlers are at just the right height
to keep the wolves at bay.
But it's now the elk that has a problem of his own.
Although it's only knee deep, he can't stay in this freezing water forever.
A young female is not prepared to let him go.
But the elk is strong.
One-on-one he has the advantage.
Her only support is another youngster.
They are neither strong or experienced enough
to bring this elk down.
But it's enough to make him turn and run
back to the river where he knows they won't follow.
它又跑回河里 它知道 它们不会跟下来
But the longer he stays in the freezing water,
the weaker he will get.
Others before him have waited here too long,
and wolves are patient.
Right now his strength is his only advantage.
He has to try again.
This time even the young wolves stay put.
Without the support of the pack they never really stood a chance.
And the pack have already decided that this early in the winter,
a bull elk in his prime is just too strong.
But as the winter gets colder
and the snow gets deeper the tables will turn.
By the end of November,
the arc of the sun barely breaks above the trees.
As its angle decreases, so does its power.
And as the sun loses its hold over the land,
other forces begin to take over.
Yellowstone has a dark secret
that affects everything that lives here,
especially in the winter.
It's only from high above ground
that we start to get a glimpse of the true nature of this place.
Yellowstone is a giant bowl 50 miles wide
right in the middle of the Rocky Mountains.
There's nowhere else like it.
And there's only one thing that could have created it.
Three miles beneath this frozen surface
is a colossal chamber of molten rock.
Today it powers Yellowstone's geysers.
But every million years or so,
the pressure in this magma gets critical and the chamber explodes.
The last eruption, 640,000 years ago,
最后一次的爆发 是在640000 年前
was more than 1,000 times larger than Mount St Helens.
It blasted away mountains and ejected hundreds of cubic miles of debris
into the atmosphere, burying half the USA with ash.
The heart of Yellowstone is one of the world's biggest volcanoes.
One day it will erupt again.
It could be today or in another million years.
But even as the volcano is sleeping,
breathing quietly through its geysers,
it has a profound effect on Yellowstone's winter.
The volcano made Yellowstone's giant bowl but it didn't stop there.
Ever since, the huge pressure below the surface
has been pushing it higher into the air,
and as it gets higher it gets colder.
And now at its present altitude of 8,000 feet,
它现在高度 是8000 英尺
this giant bowl simply accumulates freezing air
from the surrounding mountains.
In the winter, the sleeping volcano becomes a giant deep freeze.
在冬天 沉睡的火山 极度深寒
On the open plateau, right in the middle of this frozen volcano
is an animal that has lived here since the last ice age.
Bison are exposed to the worst of the Yellowstone winter,
but they are built for it.
Their thick coat is such good insulation
that they only need a tiny amount of energy to keep warm.
So they slow their metabolism right down and concentrate on feeding.
With massive neck muscles they sweep their heads down through the snow
to get to the grass beneath.
But the grass has long ago put its summer goodness down into its roots
and now has about the same nutritional value as cardboard.
They will need to do all they can to save energy
if they are to ward off starvation until spring returns.
As the winter strengthens its grip,
elk move into more sheltered valleys at the edge of Yellowstone.
They don't have the bison's ability to move deep snow.
But this brings them into the territory of the Druid pack.
As the grazers are beginning to weaken,
life for the wolves is getting easier.
They are now successfully hunting about twice a week.
They even have the energy to play.