Why is Mount Everest so tall? - Michele Koppes

譯者: Helen Chang 審譯者: Ann Chen

Every spring,

每年春天，

hundreds of adventure-seekers dream of climbing Qomolangma,

數以百計的探險者 夢想著去攀登 Qomolangma，

also known as Mount Everest.

也就是 珠穆朗瑪峰（珠峰）。

At base camp, they hunker down for months

在基地營，他們盤坐數個月，

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

等待機會攀登此峰 高聳、致命的山頂。

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

為何人們甘願冒生命危險 去攀登珠峰呢？

Is it the challenge?

是挑戰性？

The view?

風景？

The chance to touch the sky?

碰觸天的機會？

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

很多人被吸引是因為 珠峰是世界最高峰。

There's an important distinction to make here.

這裡有個重要的差別必須釐清，

Mauna Kea is actually the tallest from base to summit,

就山腳量到山頂 毛納基火山 是真正最高的山，

but at 8850 meters above sea level,

但高達海平面以上 8850 公尺

Everest has the highest altitude on the planet.

珠峰是世界海拔最高的山峰。

To understand how this towering formation was born,

要了解這座高聳的山是怎麼形成的，

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

我們必須深入地球的地殼

where continental plates collide.

去看大陸板塊的碰撞。

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

地球表面就像是一個犰狳的護甲，

Pieces of crust constantly move over,

一塊塊地殼不斷地 彼此上疊、下滑及圍繞。

under,

and around each other.

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

這些巨大大陸板塊的 移動速度算是快的，

They move two to four centimeters per year,

大約每年 2 到 4 公分，

about as fast as fingernails grow.

和我們指甲的生長速度近似。

When two plates collide,

當兩個板塊發生碰撞，

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

一塊推或滑到另一塊底下， 其邊緣會摺皺，

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

造成了所謂的「隆起」 以容納額外的地殼，

That's how Everest came about.

珠峰就是這樣形成的。

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

5 千萬年前，印度板塊北移

與更大的歐亞板塊相撞，

bumped into the bigger Eurasian Plate,

and the crust crumpled, creating huge uplift.

那裡地殼彎皺，造成巨大的隆起。

Mountain Everest lies at the heart of this action,

珠峰位於這次板塊互撞的中心處，

on the edge of the Indian-Eurasian collision zone.

在印度及歐亞板塊撞擊交接地帶。

But mountains are shaped by forces other than uplift.

除了隆起之外， 「力量」也影響了山形。

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

當陸地被往上推，氣團也被迫上升。

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

上升的空氣變冷， 造成空氣中的水蒸氣凝結，

and form rain or snow.

形成雨或雪。

As that falls, it wears down the landscape,

落下的雨與雪，磨蝕了地形，

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

溶解或分解岩石， 此過程稱為「風化作用」。

Water moving downhill carries the weathered material

水攜帶著風化物質往下沖，

and erodes the landscape,

侵蝕地表，

carving out deep valleys and jagged peaks.

刻出深谷和鋸齒狀的山峰。

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

山在隆起與侵蝕的平衡間成形。

But compare the celestial peaks of the Himalayas

若比較高聳的喜馬拉雅山峰 和平緩的阿帕拉契山丘，

to the comforting hills of Appalachia.

Clearly, all mountains are not alike.

顯而易見，山並非全是一個模樣。

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

因為「時間」也起作用的。

When continental plates first collide, uplift happens fast.

當陸塊初碰撞時， 地表隆起非常迅速，

The peaks grow tall with steep slopes.

形成既高又陡峭的山頂。

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

隨著時間流轉， 重力和水使得山形逐漸平緩。

Eventually, erosion overtakes uplift,

最終，侵蝕超越隆起，

wearing down peaks faster than they're pushed up.

山頂平緩比隆起的速度更快。

A third factor shapes mountains: climate.

「氣候」是塑造山形的第三種力量。

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

在零度以下的溫度， 部分降雪不會完全融化，

instead slowly compacting until it becomes ice.

而是逐漸壓縮成冰。

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

這就形成了「雪線」， 各地的雪線高度不同，

depending on climate.

因各地氣候而異。

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

南北極的雪線在海平面，

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

而赤道附近， 則需爬到 5000 公尺左右才夠冷，

for ice to form.

水才能結冰。

Gathered ice starts flowing under its own immense weight

聚集的冰塊， 因自身巨大重量而開始移動，

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

形成緩慢流動的冰涷河， 名為「冰河（冰川）」，

which grinds the rocks below.

碾磨在其下的岩石。

The steeper the mountains, the faster ice flows,

山形越陡峭，冰流動越快，

and the quicker it carves the underlying rock.

且切割它底下的岩石越快。

Glaciers can erode landscapes swifter than rain and rivers.

冰河侵蝕地形的速度， 遠快於雨水和河流。

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

緊附著於山頂的冰河 能快速磨平山頂，

they lop the tops off like giant snowy buzzsaws.

將山尖削下來， 如同巨大的雪圓鋸。

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

既然如此， 冰雪覆蓋的珠峰怎能這麼高呢？

The cataclysmic continental clash from which it arose

第一，那劇變的板塊撞擊， 使得珠峰一開始就非常高大。

made it huge to begin with.

Secondly, the mountain lies near the tropics,

第二，它的位置靠近赤道，

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

所以雪線高，而冰河相對是小的，

barely big enough to widdle it down.

削弱山形的力量有限。

The mountain exists in a perfect storm of conditions

在這樣的完美條件之下，

that maintain its impressive stature.

使得珠峰保持讓人印象深刻的高度。

But that won't always be the case.

但此景未必長在。

We live in a changing world where the continental plates,

我們生活在多變的世界裡，

在此，大陸板塊、

Earth's climate,

地球的氣候 及地球的侵蝕力量，

and the planet's erosive power

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

也許有一天會共同協力 削減珠峰的高度。

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

至少目前，珠峰仍是徒步旅行者， 冒險家，夢想家們，全都嚮往的傳奇。

adventurers,

and dreamers alike.