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  • The geography of our planet is in flux.

    我們星球的地形處於不斷的變動中。

  • Each continent has ricocheted around the globe on one or more tectonic plates, changing quite dramatically with time.

    全球的每一塊大陸在一個或多個板塊上游移,隨者時間劇烈的變化。

  • Today, we'll focus on North America and how its familiar landscape and features emerged over hundreds of millions of years.

    今天,我們將聚焦在北美洲這常見的地形和特徵如何出現了超過幾百萬年。

  • Our story begins about 750 million years ago.

    這個故事要從大約 7 億 5 千萬年前開始。

  • As the super continent Rodinia becomes unstable, it rifts along what's now the west coast of North America to create the Panthalassa Ocean.

    當巨大的羅迪尼亞大陸變得不穩定,它沿著今日的北美西岸裂開來形成了古太平洋。

  • You're seeing an ancestral continent called Laurentia, which grows over the next few hundred million years as island chains collide with it and add land mass.

    你可以看到一個稱為勞倫大陸的古大陸,它在接下來的幾億年增大撞上島鏈並形成巨大的陸地。

  • We're now at 400 million years ago.

    現在我們在 4 億年前。

  • Off today's east coast, the massive African plate inches westward, closing the ancient Iapetus Ocean.

    在今天的東岸外海,巨大的非洲板塊在距離幾英吋的西邊,將巨神海合併了起來。

  • It finally collides with Laurentia at 250 million years to form another supercontinent Pangea.

    最後在 2 億 5 千萬年撞上勞倫大陸形成了另一個超級大陸「盤古大陸」。

  • The immense pressure causes faulting and folding, stacking up rock to form the Appalachian Mountains.

    這巨大的壓力造成斷層和褶皺抬升岩石形成阿帕拉契山脈。

  • Let's fast forward a bit.

    讓我們再加快往前一點。

  • About 100 million years later, Pangea breaks apart, opening the Southern Atlantic Ocean between the new North American Plate and the African Plate.

    大約 1 億年後,盤古大陸分開了,在新北美板塊和非洲板塊之間拓開成南大西洋。

  • We forge ahead, and now the eastward-moving Farallon Plate converges with the present-day west coast.

    我們高速前進,現在往東邊移動的法拉龍板塊和今日的西岸聚合。

  • The Farallon Plate's greater density makes it sink beneath North America.

    密度較大的法拉龍板塊沉到了北美下方。

  • This is called subduction, and it diffuses water into the magma-filled mantle.

    這稱為「隱沒」,而水滲進充滿岩漿的地函。

  • That lowers the magma's melting point and makes it rise into the overlying North American plate.

    那降低了岩漿的熔點使它上升與北美板塊重疊。

  • From a subterranean chamber, the magma travels upwards and erupts along a chain of volcanos.

    來自地下岩漿庫的岩漿往上移動並沿著火山鍊爆發。

  • Magma still deep underground slowly cools, crystallizing to form solid rock, including the granite now found in Yosemite National Park and the Sierra Nevada Mountains.

    依然在地底深處的岩漿則慢慢冷卻,結晶形成堅固的岩石, 包括現今在優勝美地國家公園和內華達山脈找到的花崗岩。

  • We'll come back to that later.

    我們待會會再回到這。

  • Now, it's 85 million years ago.

    現在,在 8500 萬年前。

  • The Farallon Plate becomes less steep, causing volcanism to stretch eastward and eventually cease.

    法拉龍板塊不像以前陡峭,造成向東伸展並永遠停止的火山活動。

  • As the Farallon Plate subducts, it compresses North America, thrusting up mountain ranges like the Rockies, which extend over 3,000 miles.

    當法拉龍板塊開始隱沒,壓縮了北美洲洛磯山脈破土而出,延伸超過 3 千英里。

  • Soon after, the Eurasian Plate rifts from North America, opening the North Atlantic Ocean.

    不久之後,歐亞板塊從北美板塊漂移開來,開拓出北大西洋。

  • We'll fast forward again.

    我們再一次加速往前。

  • The Colorado Plateau now uplifts, likely due to a combination of upward mantle flow and a thickened North American Plate.

    現在科羅拉多高原抬升了,很可能是由於往上的地函流動以及厚實的北美板塊。

  • In future millennia, the Colorado River will eventually sculpt the plateau into the epic Grand Canyon.

    在未來的幾千年,科羅拉多河終將高原鑿成經典的大峽谷。

  • 30 million years ago, the majority of the Farallon Plate sinks into the mantle, leaving behind only small corners still subducting.

    3 千萬年前,大部分的法拉龍板塊沉進地函中,只剩下一小角落依然隱沒在下面。

  • The Pacific and North American plates converge and a new boundary called the San Andreas Fault forms.

    太平洋板塊及北美板塊聚合形成新的邊界稱做聖安德烈亞斯斷層。

  • Here, North America moves to the south, sliding against the Pacific Plate, which shifts to the north.

    在這裡,北美洲往南移向往北移的太平洋板塊。

  • This plate boundary still exists today, and moves about 30 millimeters per year, capable of causing devastating earthquakes.

    這個板塊邊界現在還存在,每年大約移動 30 毫米,有可能造成毀滅性的地震。

  • The San Andreas also pulls apart western North America across a wide rift zone.

    聖安德烈亞斯斷層也拉開了西部的北美洲形成寬闊的斷層地帶。

  • This extensional region is called the Basin and Range Province, and through uplift and erosion, is responsible for exposing the once deep granite of Yosemite and the Sierra Nevada.

    這個向外延申出來的地區被稱作盆嶺地區,經由抬升和侵蝕,造成優勝美地和內華達州深處的花崗岩暴露。

  • Another 15 million years off the clock, and magma from the mantle burns a giant hole into western North America, periodically erupting onto the surface.

    在 1 千 5 百萬年後,來自地函的岩漿將西部北美洲燒出了一個大洞,並在表面週期性地噴發。

  • Today, this hotspot feeds an active supervolcano beneath Yellowstone National Park.

    今天,這個熱點注入在黃石國家公園下的活火山。

  • It hasn't erupted in the last 174,000 years, but if it did, its sheer force could blanket most of the continent with ash that would blacken the skies and threaten humanity.

    它在過去的 174000 年都還沒噴發過,但如果噴發了, 它全部的力量會使得火山灰攏照大部分的大陸,遮蓋天空並威脅人類的生存。

  • The Yellowstone supervolcano is just one reminder that the Earth continues to seethe below our feet.

    這個黃石公園的超級火山只是一個提醒我們腳下的地球正持續沸騰著。

  • Its mobile plates put the planet in a state of constant flux.

    會移動的板塊使這個星球處於一定的流動狀態。

  • In another few hundred million years, who knows how the landscape of North America will have changed.

    在接下來幾億年中,誰會知道北美的地型會如何改變。

  • As the continent slowly morphs into something unfamiliar, only geological time will tell.

    當這塊大陸慢慢的變成另一個我們不熟悉的型態,只有地質年代會告訴我們答案。

The geography of our planet is in flux.

我們星球的地形處於不斷的變動中。

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B2 中高級 中文 美國腔 TED-Ed 板塊 大陸 岩漿 北美 形成

【TED-Ed】北美洲如何形成的呢? (How North America got its shape - Peter J. Haproff)

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    Sh, Gang (Aaron) 發佈於 2020 年 11 月 22 日
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