NARRATOR: 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. A wonderland, 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. 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 clo 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 geyrs than the rest of the world put together.
Old Faithful is Yellowstone's most well-known geyr. It shoots 5,000 gallons of water 150 feet into the air almost every hour. But the forces that fuel this spectacular display have an influence far greater than we can e 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. It's stalemate. 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 foll
ow. 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 has 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 decreas, so does its power. And as the sun los its hold over the land, other forces begin to take over. Yellowstone has a dark cret that affects everything that lives here, especially in the winter. It's only from high above ground that we start to get a glimp 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 el 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 geyrs. But every million years or so,
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the pressure in this magma gets critical and the chamber explodes. The last eruption, 64
0,000 years ago, 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 geyrs, 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 prent altitude of 8,000 feet, his giant bowl simply accumulates freezing air from the surrounding mountains. In the winter, the sleeping volcano becomes a giant deep freeze. 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 expod 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. But their play has a purpo. It fine-tunes their hunting skills and helps bond the all-important pack structure. Though there are 16 of them, they can only hunt an animal as large as an elk if they hunt as one. The strength of the pack is what will get them through the winter. Bald eagles spot carcass from miles away. But there is strong competition for a kill like this. A coyote. He has been shadowing the wolves, and moves in now they have gone. It’s December, and even the great Yellowstone River is succumbing to the cold. It's only where the water runs fast that it still runs free. It looks uncomfortably cold, but then the water, at around freezing point, can be
50 degrees warmer than the air. Under the ice there's a rich supply of stone fly larvae waiting to hatch in the spring. Dippers make the most of the few small windows to a liquid world before they shut completely. Where the water stands still it is now frozen solid. Yellowstone Lake is 136 square miles, and now completely covered in three feet of ice. A coyote travels across this frozen dert looking for something to eat. ]It's a wonder that anything can survive here at all. Hundreds of feet beneath him on the lake bed, geyrs erupt just like they do on land 于园翻译and they melt holes in the ice, the only sign that there is a lake here at all.
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As the year comes to an end, it ems hard to imagine this winter getting any tougher. But there's another twist to the volcano's story that is about to make things even wor. Over time the continent of North America has moved, inch by inch, over many millions of years.
[21:38.87]
[21:40.64]But deep down below the Earth's moving crust,
[21:43.71]
[21:43.80]the source of magma that fuels Yellowstone's volcano
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[21:47.39]
[21:48.12]has stayed put.
nuts是什么意思[21:49.79]
[21:58.00]As the crust has moved over this volcanic hotspot,
[22:02.39]
[22:02.48]eruption after eruption has blasted a massive 500-mile-long scar
[22:07.47]
[22:07.56]right through the Rockies.
[22:09.59]
[22:15.96]In the winter this giant scar, called the Snake River Plain,
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[22:20.88]funnels moist air from the Pacific Ocean
[22:24.07]
[22:24.16]right through the wall of the Rocky Mountains
[22:26.87]
[22:26.96]and up into Yellowstone's deep freeze.
[22:29.63]
[22:36.04]Here it finally freezes and falls as snow,
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[22:41.16]huge quantities of it.
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[22:42.99]
[23:00.04]Whilst everywhere around gets 10 feet of snow a year,
[23:03.71]
[23:03.80]thanks to the legacy of its volcano, Yellowstone can get as much as 50.
[23:08.66]
[23:18.56]Otters em to thrive in the Yellowstone winter.
[23:21.79]
[23:31.52]But now that the rivers are not only frozen but covered in deep snow,
[23:36.27]
[23:36.36]they are struggling to find open water to fish in.
[23:39.55]
[23:56.00]They can't fish here, the fast flowing water is too dangerous.
[24:00.55]
[24:00.64]Somehow they need to find a way past the falls.
[24:03.79]
[24:53.64]With the falls safely behind them, the otters are forced to keep moving on.
