章节大纲

  • 常规

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  • 地球历史和化石线索

    Snow-covered mountains with a sunrise, illustrating geological history connected to seashells.
     

    How could there be seashells at 20,000 feet?
    ::怎么会有20,000英尺高的贝壳呢?

    Shell beds are found high in the Andes  Mountains . How did they get there? This is more evidence that Earth is a dynamic planet! The   that is on top of the mountains was once beneath the sea. Due to  plate tectonics , the mountains rose slowly above the ocean. This process took a really long time. This is one way we know that Earth is really old!
    ::贝壳床在安第斯山脉高处被发现。 它们是如何到达那里的? 这是地球是一个充满活力的星球的更多证据。 山顶的山顶曾经在海底下。 由于板块构造, 山峰慢慢地在海洋之上升起。 这个过程花了很长的时间。 这是我们知道地球真的老了的一种方式 。

    Learning from Fossils
    ::从化石中学习

    Of all the organisms that ever lived, only a tiny number became  fossils . Still, scientists learn a lot from fossils. Fossils are our best clues about the history of life on Earth.
    ::然而,科学家还是从化石中学到了很多东西。 化石是我们关于地球上生命史的最好线索。

    Fossil Clues
    ::化石结壳

    Fossils give clues about major geological events. Fossils, like the one pictured below ( Figure ), can also give clues about past climates. Here are just a few examples.
    ::化石提供了重大地质事件的线索。 化石像下面的图( Figure ) 一样, 也可以提供过去气候的线索。 这里仅举几个例子。

    • Fossils of ocean animals are found at the top of Mt. Everest. Mt. Everest is the highest mountain on Earth. These fossils show that the area was once at the bottom of a sea. The seabed was later uplifted to form the Himalaya mountain range.
      ::在珠穆朗玛峰顶端发现了海洋动物的化石,珠穆朗玛峰是地球上最高的山,这些化石表明该地区曾一度位于海底,后来海床升起形成喜马拉雅山脉。
    • Fossils of plants are found in Antarctica. Currently, Antarctica is almost completely covered with ice. The fossil plants show that Antarctica once had a much warmer  climate .
      ::南极洲有植物的化石。目前南极洲几乎完全被冰覆盖。化石工厂显示南极洲曾经有更温暖的气候。
    Fossil of a fish, illustrating clues about Earth's geological and climatic history.
     
    What can we learn from fossil clues like this fish fossil found in the Wyoming desert?

    Index Fossils
    ::化石指数

    Fossils are used to determine the ages of rock layers.  Index fossils  are the most useful for this. Index fossils are of organisms that lived over a wide area. They lived for a fairly short period of time. An index fossil allows a scientist to determine the age of the rock it is in.
    ::化石用于确定岩石层的年代。 指数化石对此最有用。 指数化石是居住在大片地区的生物。 它们居住的时间相当短。 指数化石让科学家可以确定岩石的年代。

    Trilobite fossils ( Figure  ) are common index fossils. Trilobites were widespread marine animals. They lived between 500 and 600 million years ago. Rock layers containing trilobite fossils must be that age. Different  species  of trilobite fossils can be used to narrow the age even more.
    ::Trilobite 化石( Figure ) 是常见的指数化石。 Trilobites是广泛的海洋动物,它们生活在五亿到六亿年前。 含有三lobite 化石的岩石层必须在这个年代。 不同的三lobite 化石种类可以用来进一步缩小年龄。

    A collection of trilobite fossils displayed on a paleontological exhibit.
     
    Trilobites are good index fossils. Why are trilobite fossils useful as index fossils?

     

    Summary
    ::摘要

    • Fossils tell a lot about the environment during the time they were deposited.
      ::化石在沉积期间 告诉了很多环境
    • Climate is one important thing that can be indicated by fossils. This is because organisms have specific conditions in which they can live.
      ::气候是化石可以显示的重要事物之一。 这是因为生物有他们可以生存的特定条件。
    • An index fossil must be distinctive, widespread, and short-lived. It indicates a specific period of time.
      ::指数化石必须是独特、广泛和短暂的。 它表明一个特定的时间段。

    Review
    ::回顾

    1. How do fossils help geologists learn about the geological history of an area?
      ::化石如何帮助地质学家了解一个地区的地质史?
    1. How is an index fossil used to identify a time period?
      ::指数化石如何用来确定一个时期?
    1. Why are the fossils of marine organisms sometimes found in rock units at the tops of high mountains? What does this tell you about the geological history of an area?
      ::为什么海洋生物的化石有时会在高山顶的岩石单位中发现? 这告诉了你一个地区的地质史吗?

    Explore More
    ::探索更多

    Use the resource below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    1. Why is the paleoecologist collecting samples?
      ::为什么古生物学家要采集样本?
    1. What does he want to create from the fossil evidence?
      ::他想从化石证据中创造什么?
    1. How is this similar to forensic science?
      ::这和法医学有什么相似之处?
    1. What do they look for to understand insect feeding?
      ::他们想了解昆虫喂食什么?
    1. What has been discovered from these fossils?
      ::从这些化石中发现了什么?
    1. What question does this raise for the scientists?
      ::这给科学家带来了什么问题?