地球 独一无二的星球 Earth -- a unique planet
瞬息万变 永不休止 restless and dynamic.
大陆板块迁移碰撞 Continents shift and clash.
火山爆发 冰川凝结消融 Volcanoes erupt, glaciers grow and recede.
巨大的力量不断作用 Titanic forces that are constantly at work,
留下一系列地质谜题 leaving behind a trail of geological mysteries.
本期内容主要探索冰川 This episode journeys back through time
是如何塑了造当代的北美洲 to explore how ice has shaped modern North America.
地质学家发现了美国的气温 Geologists discover how America's temperatures plunged
是如何骤降至整年都在零下三度的 to an average of 26 degrees Fahrenheit all year round,
一片相当于 how a wall of ice
帝国大厦八倍高的冰川 8 times the height of the Empire State building
是如何覆盖了北美洲大部分地区的 covered much of North America,
冰川是如何创造了这个国家 and how ice created some of the country's most stunning
最为神奇的地理奇观的 geological wonders.
《地球的起源》的新一期 A deep-frozen episode in the continuing drama
震撼人心的节目 of "How the Earth Was Made."
美洲的冰川世纪 America's Ice Age
在北美洲现代风貌的形成过程中 One awesome physical force
冰川这股永不休止的力量 has had more impact than any other
扮演的角色比其他的力量 on the shaping of modern North America--
更为重要 the dynamic, unstoppable power of ice.
数百万年前 Over millions of years,
一片一千六百多米厚 甚至更厚的冰川 ice sheets a mile or more thick
从这片大陆的高山上迁徙而过 have decapitated the continent's mountains
改变了河流的流向 and dammed and diverted its rivers.
但是只有当科学家们调查了 But the full extent
美洲冰川世纪造成的地质影响时 of how ice has carved and sculpted the landscape of the U.S.
冰川对塑造 is only now becoming clear
美国的地理外貌起到的巨大作用 as scientists investigate the overwhelming geological impact
才变得明晰 of America's Ice Age.
几个世纪以来 美国早期的地质学家 For centuries, America's early geologists were puzzled
对北美洲大陆 by mysterious marks etched
大部分基岩上的神秘的印记 into the bedrock of much of North America
和散落在大陆上一些的岩石 and by lonely mounds of rock
都困惑不已 randomly scattered across the land.
许多地质学家认为这是很久以前 Many believed such features were evidence of a massive flood
大规模的洪水留下的痕迹 in the long-distant past,
直到一八四七年 but then in 1847,
一位哈佛大学新上任的教授 a newly appointed Harvard university professor
提出了一项全新的理念 came up with a radical new idea.
地质学家Louis Agassiz Geologist Louis Agassiz
将北美洲的地貌和岩石风貌 compared North America's landscape and rocks
和他的祖国瑞士的山地冰川做了对比 with the geology of mountain glaciers in his native Switzerland,
基于他十年前研究的 and he built on theories he had developed
瑞士阿尔卑斯山脉的理论 in the Swiss Alps a decade earlier
他得出北美洲曾经被冰川覆盖 to declare that North America had once been buried
这一结论 deep under ice.
Agassiz在哈佛大学的研究 Agassiz's work at Harvard
在他那个时代举世皆知 made him world-famous in his day,
但是他的冰川世纪的理论 but the final proof of his Ice Age theory
直到二十世纪五十年代才被最终证实 had to wait until the 1950s,
这些证据来自太平洋底的海床 when new evidence came from the seabed of the Atlantic Ocean.
那个证据直到现在还被储存在 That evidence is still stored to this day
迈阿密大学的这间冷冻实验室 in this refrigerated laboratory at Miami University.
这里数千根的塑料管 These thousands of plastic tubes
为科学家研究远古时代 offer scientists a unique window
地球的温度情况提供了独特的视野 to look back at what the weather was like on the ancient Earth.
你在这间房间里看到的这些证据 These records which you see in this room here
人名1
基本都是我们现在 basically are the primary information we have now
拥有的关于两百万年间 about the climate changes we have
环境变迁的一些基本信息 had over the last two million years,
这些证据却是是帮助我们 so these really were the starting points
了解冰川世纪时环境的变迁的 that opened people's eyes about
最一手的资料 changes which occurred during glacial periods.
这些泥柱是由海洋学家Cesare Emiliani收集的 The mud cores were collected by oceanographer Cesare Emiliani.
他钻的越深 The deeper he drilled,
他带回来的样品的 the further back in time he went
所处的时代就越久远 and the older the sample he pulled to the surface.
这些是深海泥柱 These are cores of deep-sea mud,
在泥柱里面有些小的生物 and within the mud are small organisms
这些生物记录了当时的气温 which record the temperature
盐度还有该生物生存时代的 and the salinity and the other conditions
其他的一些基本情况 which were prevalent when that organism lived.
这些微小的海底生物被称为孔虫 Those tiny undersea creatures are called foraminifera.
它们的化学组成 Their chemical makeup varies
因他们生活水域的气温而异 depending on the temperature of the water in which they grow,
所以这些位于不同泥层的海虫 so the sea bugs in different layers of mud
就像是迷你温度计 act as tiny thermometers
记录了它们生活的不同时代的 recording how hot or cold the Earth was
地球的气温 at different times in its past.
它们表明两百多万年前 They reveal that just over two million years ago,
美国北面的四十八个洲的年平均气温 the average annual temperature across the lower 48 states
约为十三摄氏度 was around 56 degrees Fahrenheit,
比现在的温度高三度 about 3 degrees warmer than it is today.
然后气温开始慢慢的下降到零度以下 Then the temperature regularly started crashing below zero
然后一直维持在这个温度 and stayed there for month after month.
从地理角度来看 Huge changes happened
这个变化属于瞬息万变了 with what in geological terms was astonishing speed.
在之后的一万年内 Within 10,000 years,
整年的平均气温都维持在 the year-round average temperature bottomed out
零下三度 at just 26 degrees Fahrenheit,
相当于芝加哥冬天的平均气温 the same as the average winter temperature in Chicago.
即使现在 科学家们还是不确定 Even today, scientists are uncertain
是什么导致了气温的骤降 what caused the temperature to drop so quickly.
地球轨迹的变化 Variations in the Earth's orbit,
地球轴线的改变 a change in the tilt of its axis,
甚至是喜马拉雅山脉的形成 and even the creation of the Himalayan Mountain range
都是主要的嫌疑 are all prime suspects,
但有一件事情是确定的 but one thing is certain.
当整年的温度都维持在零度以下时 With subzero temperatures all year round,
整天应该都是冰天雪地的 snow never melted.
一场大的雪暴可以造成四千万吨的降雪 A major storm can drop more than 40 million tons of snow.
积压的雪越来越重 The ever-increasing weight compacted down
慢慢的在地面形成了一层厚厚的冰层 into thick layers of solid ice.
美国的冰川世纪就此开始 America's Ice Age had begun.
接下来发生的事情的重要线索 An important clue to what happened next
就隐藏在伊利诺伊州 lays in a rock quarry
CHAMPAIGN
Champaign镇外的采石场内 just outside the town of Champaign, Illinois.
在像这样的采石场里面 In quarries like this,
位于地下的石头往往 rocks normally hidden deep underground
会因商业爆破暴露出来 are exposed by commercial blasting.
这为地质学家研究 That gives geologists the chance
难得一见的岩石提供了很好的机会 to examine rocks they could never normally see.
这块位于鹅卵石沙层的岩石 This rock in the sandy, cobbly bank
是研究北美洲 is a very important and significant piece of evidence
人名2
在过去几十万年内的历史的 for the history of North America
极为重要的证据 during the last several hundred thousand years.
我们称其为非正常现象 It's what we call an erratic.
这块岩石不属于这个地方 It's a rock that doesn't belong here.
这块岩石长途跋涉了几百公里 This rock traveled several hundred miles
才到这个地方落脚 to get to this place.
事实上 这种石英石一般都在加拿大 In fact, this is a type of granite usually found in Canada.
但是 它却来到了伊利诺伊州 Somehow, it has traveled to Illinois,
这样的情况并非仅此一例 but it's not unique.
在整个北部的州内 All over the northern states,
各种奇形怪状的石头 rocks of all shapes and sizes
出现在了不属于它们的地方 have been dumped in places they don't belong.
这块 位于纽约州 中央公园的 This one, the size of an elevator,
电梯这么大的岩石 is in Central Park, New York.
来自于新泽西州 It was originally from New Jersey.
还有这块 And this one,
像汽车那么大那么重的石头 the size of an automobile and weighing just as much,
来自北边八百多公里的安大略省 comes from 500 miles north of Ontario.
科学家们已经弄清楚了 Scientists have figured out
这么大的岩石是如何 just how such huge rocks must have been transported
长途跋涉的 over such long distances.
两百万年前 The ice sheets
形成的冰层开始移动 which built up two million years ago began to move,
冰川穿越了美国的北部 flowing as huge glaciers across the northern U.S.
一些大的岩石 Some of the very large rocks
原先是被冻住了 后来 can be literally frozen on and plucked off
被从原来的石头上就地拔起 from the rock where they came from
正好和冰川融为一体 and transported right in the glacier
和冰川一起长途跋涉 and moved that distance of hundreds of miles
冰川就像传输带将岩石运送到了 in the glacier like a conveyor belt
我们最终发现它的地方 out to where we finally find it
变成景观 或者像这样裸露在外 on the landscape or in an outcrop like this.
调查者的下一个挑战 The investigators' next challenge
是弄清楚冰川迁徙了多远 is finding out just how far the ice flowed,
为了实现这一目的 他们进行了空中勘测 and for that task, they are taking to the air.
在清晨的阳光中 In the early-morning light,
Brown发现了一处神秘的小山丘 Brown spots a mysterious, small hill
在伊利诺伊州的平原上 standing out
这处山丘尤为引人注目 from the flat Illinois plain.
撇开它外层的厚厚的树木 Stripped of its camouflage layer of trees,
山丘的形状告诉了Brown它形成的秘密 the shape of the hill tells Brown the secrets of its creation.
这片地貌绵延了 This gently rolling landscape
约六百四十三公里 extends for about 400 miles.
我们看着地貌和地貌的形成 We look at the landforms and how they're shaped,
这样就能用以 and so we can use that