Superb The Changing Earth
第 1 單元，第 1 課

Moving Continents移動的大陸

這課一眼看
The continental drift hypothesis大陸漂移假說
  • supercontinent超大陸: One huge landmass made of many continents.
  • Pangaea盤古大陸: Supercontinent that began breaking apart about 200 million years ago.
  • continental drift大陸漂移: Hypothesis that continents were joined and slowly drifted apart.
  • hypothesis假說: Possible explanation that can be tested.
  • continental shelf大陸棚: Edge of a continent under shallow ocean water.
Clues from climate and fossils氣候與化石的線索
  • glacial groove冰川擦痕: Deep scratch in rock made by a moving glacier.
  • fossil化石: Preserved remains or traces of an ancient organism.
  • Gondwana岡瓦納大陸: Ancient southern landmass of joined continents.
  • Laurasia勞亞大陸: Ancient northern landmass of joined continents.
Why scientists doubted Wegener為什麼科學家懷疑韋格納
    1The continental drift hypothesis大陸漂移假說

    AWegener and Pangaea韋格納與盤古大陸

    1. Early mapmakers noticed that the coastlines of some continents, such as South America and Africa, look like they could fit together like puzzle pieces.早期的地圖繪製者注意到，有些大陸的海岸線（例如南美洲和非洲）看起來可以像拼圖一樣拼在一起。
    2. In 1912, Alfred Wegener proposed that all the continents were once joined in one huge landmass, a supercontinent he called Pangaea. He suggested that Pangaea broke apart and the pieces slowly moved to where they are today.1912 年，韋格納提出所有大陸曾經連在一起，形成一塊巨大的陸地，也就是他稱為盤古大陸的超大陸。他認為盤古大陸後來分裂，碎塊慢慢移動到今天的位置。
    3. This idea is called continental drift. It was a hypothesis: a possible explanation that still needed evidence to support it.這個想法稱為大陸漂移。它是一個假說：一種可能的解釋，仍然需要證據支持。

    BEvidence from shape and rocks形狀與岩石的證據

    1. The fit is even better when you match the edges of the continental shelves, the parts of each continent that lie under shallow ocean water.如果比對大陸棚的邊緣，拼合得更吻合。大陸棚是大陸位於淺海底下的部分。
    2. Rocks of the same type and age are found on opposite sides of the Atlantic Ocean. For example, volcanic rocks on the west coast of Africa and the east coast of South America have the same chemistry and age.大西洋兩岸可以找到種類和年代相同的岩石。例如，非洲西岸和南美洲東岸的火山岩，化學成分和年代都一樣。
    3. Some mountain ranges also line up across the ocean when the continents are put back together, as if one mountain chain was split apart.把大陸拼回去時，有些山脈也會跨越海洋連成一線，好像一條山脈被拆開了。
    2Clues from climate and fossils氣候與化石的線索

    AEvidence from past climates古氣候的證據

    1. Wegener found glacial grooves, deep scratches that moving glaciers leave on rock, about 290 million years old in places that are warm today, such as South America, Africa, India, and Australia.韋格納在南美洲、非洲、印度和澳洲等現在溫暖的地方，發現約 2.9 億年前的冰川擦痕，也就是冰川移動時在岩石上刮出的深溝。
    2. Glaciers could not have formed there in their present positions, so these continents must once have been closer to the South Pole.這些大陸在現在的位置不可能形成冰川，所以它們以前一定比較靠近南極。
    3. Coal forms from plants in warm, wet swamps, yet coal has been found in Antarctica. This shows that Antarctica was once much closer to the equator.煤是由溫暖潮溼沼澤中的植物形成的，但南極洲也發現了煤。這表示南極洲以前離赤道近得多。

    BEvidence from fossils化石的證據

    1. Fossils of the same land plants and animals have been found on continents now separated by wide oceans. Fossils are preserved remains or traces of ancient organisms.在現在被廣大海洋隔開的大陸上，發現了相同陸生動植物的化石。化石是古代生物保存下來的遺骸或痕跡。
    2. The plant Glossopteris is found in South America, Africa, India, Australia, and Antarctica. The reptile Mesosaurus lived in fresh water and could not have swum across an ocean, yet its fossils are found in both South America and Africa.舌羊齒這種植物的化石出現在南美洲、非洲、印度、澳洲和南極洲。中龍是生活在淡水中的爬行動物，不可能游過大洋，但南美洲和非洲都有它的化石。
    3. The simplest explanation is that these continents were joined when the organisms lived. Scientists call the southern part of the ancient landmass Gondwana and the northern part Laurasia.最簡單的解釋是：這些生物生存時，這些大陸是連在一起的。科學家把古代大陸的南半部稱為岡瓦納大陸，北半部稱為勞亞大陸。
    Evidence for continental drift大陸漂移的證據
    Evidence證據What was found發現了什麼What it suggests代表什麼
    Fit of continents大陸拼合Coastlines and continental shelves match海岸線與大陸棚吻合Continents were once joined大陸曾經相連
    Rocks and mountains岩石與山脈Same rock types and ages, matching mountain chains across oceans大洋兩岸岩石種類、年代相同，山脈相接Rock formations were split apart岩層被分開
    Glacial grooves冰川刮痕Grooves in now-warm places現今溫暖地區有冰川刮痕Continents were once near the South Pole大陸曾靠近南極
    Coal煤Coal in Antarctica南極洲有煤Antarctica was once near the equator南極洲曾靠近赤道
    Fossils化石Same land fossils on separated continents分隔的大陸上有相同的陸生化石Organisms lived on joined land生物曾生活在相連的陸地上
    3Why scientists doubted Wegener為什麼科學家懷疑韋格納

    AThe missing mechanism缺少的機制

    1. Most scientists rejected continental drift during Wegener’s lifetime. He could not explain what force could move continents or how solid continents could plow through the solid ocean floor.在韋格納有生之年，大多數科學家都不接受大陸漂移。他無法解釋是什麼力量能推動大陸，也無法說明堅硬的大陸如何穿過堅硬的海底。
    2. The evidence that answered this question was hidden on the ocean floor. It was not discovered until decades after Wegener died in 1930.回答這個問題的證據藏在海底，直到韋格納 1930 年過世幾十年後才被發現。
    自我檢查
    Did Wegener’s idea fail because his evidence was wrong?韋格納的想法沒被接受，是因為他的證據錯了嗎？
    看答案
    No. His evidence from coastlines, rocks, climate clues, and fossils was correct. What was missing was an explanation of how continents move.不是。他的海岸線、岩石、古氣候和化石證據都是對的，缺少的是大陸「如何」移動的解釋。

    這課的重點字

    • supercontinent超大陸
    • Pangaea盤古大陸
    • continental drift大陸漂移
    • hypothesis假說
    • continental shelf大陸棚
    • glacial groove冰川擦痕
    • fossil化石
    • Gondwana岡瓦納大陸
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