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  • Every spring,

    每年到了春天,

  • hundreds of adventure-seekers dream of climbing Qomolangma,

    總有數以百計的冒險者夢想著攀上珠穆朗瑪峰,

  • also known as Mount Everest.

    又稱埃佛勒斯峰。

  • At base camp, they hunker down for months

    他們在基地營休養生息數月之久,

  • waiting for the chance to scale the mountain's lofty, lethal peak.

    靜候攀登死亡高峰的最佳時機。

  • But why do people risk life and limb to climb Everest?

    是什麼驅使人們冒著喪命或截肢的危險,也要登上此峰?

  • Is it the challenge?

    是為了挑戰?

  • The view?

    為了美景?

  • The chance to touch the sky?

    為了觸摸天際?

  • For many, the draw is Everest's status as the highest mountain on Earth.

    對許多人而言,最大的原因就是它身為地球第一高峰的名號。

  • There's an important distinction to make here.

    登上此峰將使一切改觀。

  • Mauna Kea is actually the tallest from base to summit,

    事實上,毛納基火山才是從山腳到山顛最高的山峰,

  • but at 8850 meters above sea level,

    不過埃佛勒斯峰高於海平面8850公尺,

  • Everest has the highest altitude on the planet.

    它則是地球表面最高的山。

  • To understand how this towering formation was born,

    要弄懂這造塔運動的原理,

  • we have to peer deep into our planet's crust,

    我們得深入地殼內部,

  • where continental plates collide.

    在此大陸板塊彼此碰撞。

  • The Earth's surface is like an armadillo's armor.

    地球的表面就好像犰狳的盔甲一般。

  • Pieces of crust constantly move over,

    一片片的地殼不斷地彼此擠壓,

  • under,

    向上或向下,

  • and around each other.

    甚至繞著對方打轉都有可能。

  • For such huge continental plates, the motion is relatively quick.

    以大陸板塊如此巨大的體積來看,他們移動的速度算快了。

  • They move two to four centimeters per year,

    每年以2~4公分的速度移動著,

  • about as fast as fingernails grow.

    約等於指甲生長的速度。

  • When two plates collide,

    當兩個板塊碰撞時,

  • one pushes into or underneath the other, buckling at the margins,

    一塊會擠入或鑽入另一塊,造成邊緣蜷曲

  • and causing what's known as uplift to accommodate the extra crust.

    這導致了我們熟知的地殼隆起。

  • That's how Everest came about.

    埃佛勒斯峰就是如此生成的。

  • 50 million years ago, the Earth's Indian Plate drifted north,

    5000萬年以前,印度洋板塊向北漂移,

  • bumped into the bigger Eurasian Plate,

    並與體積較大的歐亞板塊撞在一塊,

  • and the crust crumpled, creating huge uplift.

    使得地殼彎曲,形成巨大的隆起。

  • Mountain Everest lies at the heart of this action,

    埃佛勒斯峰剛好地處這次板塊運動的中心位置,

  • on the edge of the Indian-Eurasian collision zone.

    位於印度、歐亞板塊撞擊區的邊緣。

  • But mountains are shaped by forces other than uplift.

    不過山脈的塑型受到隆起以外的力量所影響。

  • As the land is pushed up, air masses are forced to rise as well.

    地表被推升的同時,空氣也隨之受到影響而上升。

  • Rising air cools, causing any water vapor within it to condense

    上升的空氣因為溫度下降,致使其中的水蒸氣凝聚

  • and form rain or snow.

    進而形成雨滴或雪。

  • As that falls, it wears down the landscape,

    隨後雨滴或雪滴下,侵蝕了地表,

  • dissolving rocks or breaking them down in a process known as weathering.

    使岩石溶解或碎裂,此過程稱作風化。

  • Water moving downhill carries the weathered material

    水從山頂往山下流會順便夾帶風化後的碎片,

  • and erodes the landscape,

    同時侵蝕地表,

  • carving out deep valleys and jagged peaks.

    刻畫出深深的山谷與高聳的山峰。

  • This balance between uplift and erosion gives a mountain its shape.

    抬升與侵蝕的拉鋸給予山脈今日的面貌。

  • But compare the celestial peaks of the Himalayas

    可是,仰望直指雲端的喜馬拉雅山,

  • to the comforting hills of Appalachia.

    再看看平緩的阿帕拉契山丘。

  • Clearly, all mountains are not alike.

    很明顯可發現每座山的外觀大不相同。'

  • That's because time comes into the equation, too.

    因為還得把「時間」這個因子列入考量。

  • When continental plates first collide, uplift happens fast.

    大陸板塊互相碰撞時,抬升的速度混愾。

  • The peaks grow tall with steep slopes.

    山頂會因此帶有陡峭的斜坡。

  • Over time, however, gravity and water wear them down.

    不過隨著光陰流逝,地心引力和流水的雙重作用,會逐漸將它削平。

  • Eventually, erosion overtakes uplift,

    直到侵蝕取代抬升,

  • wearing down peaks faster than they're pushed up.

    即下降的速度快於上升。

  • A third factor shapes mountains: climate.

    第三個影響山的外觀的因子:氣候。

  • In subzero temperatures, some snowfall doesn't completely melt away,

    在零度下低溫的環境哩,落雪並不會完全融化,

  • instead slowly compacting until it becomes ice.

    反之,它們會慢慢壓實,而後變成冰。

  • That forms the snowline, which occurs at different heights around the planet

    這形成了雪線,其高度在全球的各地都不盡相同,

  • depending on climate.

    得視氣候而定。

  • At the freezing poles, the snowline is at sea level.

    在冰凍的極區,雪線高度就等於海平面。

  • Near the equator, you have to climb five kilometers before it gets cold enough

    赤道附近,得往上爬5000公尺,

  • for ice to form.

    溫度才低到足以化雪為冰。

  • Gathered ice starts flowing under its own immense weight

    聚集成堆的冰因自身重量而開始滑動,

  • forming a slow-moving frozen river known as a glacier,

    這移動速度緩慢的冰凍之河就叫冰河。

  • which grinds the rocks below.

    冰河會不斷磨擦其底下的岩石。

  • The steeper the mountains, the faster ice flows,

    山的坡度越陡,冰河流速越快,

  • and the quicker it carves the underlying rock.

    刻蝕底下岩石的速度也跟著加快。

  • Glaciers can erode landscapes swifter than rain and rivers.

    冰河侵蝕地表的功力超過了下雨和河流。

  • Where glaciers cling to mountain peaks, they sand them down so fast,

    由於冰河緊貼著山壁,它們可以快速地將之磨平,

  • they lop the tops off like giant snowy buzz saws.

    效率跟用雪做成的巨大電鋸砍樹一樣好。

  • So then, how did the icy Mount Everest come to be so tall?

    那麼,埃佛勒斯峰到底是如何長這麼高的?

  • The cataclysmic continental clash from which it arose

    生於冰河時期的大陸巨變,

  • made it huge to begin with.

    造就了埃佛勒斯峰先天傲人的高度。

  • Secondly, the mountain lies near the tropics,

    第二是,位處熱帶地區,

  • so the snowline is high, and the glaciers relatively small,

    雪線很高導致冰河相對較小,

  • barely big enough to whittle it down.

    缺乏刻蝕山體的力量。

  • The mountain exists in a perfect storm of conditions

    天時、地利具備,

  • that maintain its impressive stature.

    埃佛勒斯峰便得以保持峗然聳立之姿至今。

  • But that won't always be the case.

    但事情不會總是一成不變。

  • We live in a changing world where the continental plates,

    身處一個瞬息萬變的世界,

  • Earth's climate,

    大陸板塊,地球的氣候,

  • and the planet's erosive power

    還有地球侵蝕的力量,

  • might one day conspire to cut Mount Everest down to size.

    終將會有聯手將埃佛勒斯峰夷為平地的一天。

  • For now, at least, it remains legendary in the minds of hikers,

    至少時至今日,

  • adventurers,

    對登山者、冒險家、和追夢者等人,

  • and dreamers alike.

    埃佛勒斯峰依然在他們心中保有傳奇的地位!

Every spring,

每年到了春天,

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B2 中高級 中文 美國腔 TED-Ed 板塊 冰河 地殼 大陸 速度

【TED-Ed】聖母峰如何成為世界第一高峰? (Why is Mount Everest so tall? - Michele Koppes)

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    Yuan Jui Yu 發佈於 2016 年 06 月 18 日
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