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  • General

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  • 冰川沉积

    A snowy landscape with rocky debris, showcasing glacial erosion and deposition effects.

     

    How could those rocks on the glacier modify the landscape?
    ::冰川上的岩石如何改变地貌?

     modify the  landscape  by  erosion . They also modify the landscape by deposition. Glaciers carry an enormous amount of material and dump it. The features they leave behind show where they were and what happened as they were melting away.
    ::它们通过侵蚀来改变地貌。 它们也通过沉积来改变地貌。 冰川携带大量材料, 丢弃它。 它们留下的特征显示了它们的位置和它们融化时发生的情况。

    Deposition by Glaciers
    ::冰川沉积

    As glaciers flow,   loosens   on the  valley  walls. These rocks falls onto the glacier. Glaciers can carry rocks of any size, from giant boulders to silt. The glacier may carry the rocks for many kilometers over many years. Glaciers deposit the  sediment  when they melt. They drop and leave behind whatever was once frozen in their ice.
    ::随着冰川的流逝,山谷的墙壁会松动。这些岩石落在冰川上。冰川可以携带任何大小的岩石,从巨石流到淤泥。冰川可以携带许多年的岩石。冰川在融化时会沉积在沉积物中。它们会掉落并留下曾经被冰冻在冰中的东西。

    Erratics
    ::电极

    Giant rocks carried by a glacier are eventually dropped. These  glacial erratics , like the one pictured below ( Figure   ), are noticeable because they are huge. Also, they are usually a different rock type from the surrounding bedrock.
    ::冰川所携带的巨石最终会被抛落。这些冰川的不稳定性,如下图所示的(图 ) , 是显而易见的,因为它们巨大。此外,它们通常是与周围基岩不同的岩石类型。

    Large glacial erratics on smooth rock surface in Yosemite National Park.

     

    These glacial erratics at Yosemite National Park was deposited by a glacier.
    ::这些在约塞米特国家公园的冰川变异 是由冰川沉积的

    Glacial Till
    ::冰川直到

    The material dropped by a glacier is usually a mixture of particles and rocks of all sizes. This unsorted pile is called  glacial till .  Water  from the melting ice may form  lakes  or other water features.  Figure    shows some of the  landforms  glaciers deposit when they melt.
    ::冰川丢弃的物质通常由各种大小的颗粒和岩石混合而成,这种未分类的堆积称为冰川,融化的冰层产生的水可能形成湖泊或其他水特征。图显示一些冰川融化时的地形沉积。

    • A  moraine  is sediment  deposited  by a glacier. A  ground moraine  is a thick layer of sediments left behind by a retreating glacier. An  end moraine  is a low ridge of sediments deposited at the end of the glacier. It marks the greatest distance the glacier advanced.
      ::Moraine是冰川沉积的沉积物,地下Moraine是冰川退缩留下的厚厚的沉积物层,最后的Moraine是冰川尽头沉积的低沉积脊,是冰川前进的最远处。

    Hikers on a moraine with snow-capped mountains and a clear blue sky.

     

    The hikers are standing on a moraine. What erosional feature is the hikers looking at?
    ::徒步旅行者们站在一个山丘上。 徒步旅行者们在看什么侵蚀特征?

    • A  drumlin  is a long, low  hill  of sediments deposited by a glacier. Drumlins often occur in groups called drumlin fields. The narrow end of each drumlin points in the direction the glacier was moving when it dropped the sediments.
      ::鼓林是一个由冰川沉积的沉积物堆积的长低山丘,德鲁姆林经常在被称为鼓林田的群落中出现。 当冰川沉积下来时,每个鼓林点向冰川方向移动的狭端。
    • An  esker  is a winding ridge of sand deposited by a  stream  of meltwater. Such streams flow underneath a retreating glacier.
      ::螺旋桨是融化水流沉积的沙丘,这种流水流在退缩的冰川下流。
    • A  kettle lake  occurs where a chunk of ice was left behind in the till of a retreating glacier. When the ice melted, it left a depression. The meltwater filled it to form a lake. You can see examples of kettle lakes below ( Figure   ).
      ::当冰融化时,它留下了一片冰块。当冰融化时,它留下了一种压抑。融化的水填满了它,形成一个湖。你可以看到下面的水壶湖的例子(图 ) 。

    Aerial view of kettle lakes in Siberia, formed by melting glacial ice.

     

    Kettle lakes are found where ice sheets once covered the land. These are in Siberia.
    ::克特尔湖曾覆盖过这片土地 位于西伯利亚

    Varves
    ::变形

    Several types of stratified deposits form in glacial regions but are not formed directly by the ice.  Varves  form where lakes are covered by ice in the winter. Dark, fine-grained clays sink to the bottom of the lake in winter. Melting ice in the spring brings running water that deposits lighter colored sands. Each alternating dark/light layer represents one  year  of deposits.
    ::在冰川地区形成几种分层的矿床形式,但并非由冰直接形成。 在冬季湖泊被冰覆盖的地方形成各种变体。 黑暗的细细粘土在冬季沉入湖底。 泉水中融化的冰能带来自来水,能储存较轻的彩色沙子。 每个交替的黑/光层代表一年的矿床。

     

     

    Summary
    ::摘要

    • Glaciers dump glacial till. Glacial moraines outline a glacier's extent.
      ::冰川薄膜描绘了冰川的范围
    • Drumlins, eskers, and kettle lakes are features made of glacial till.
      ::德拉姆林、埃斯克和茶壶湖是冰川的特征。
    • Varves form in lakes covered by ice. Varves are useful to scientists for understanding climate.
      ::在冰覆盖的湖泊中,各种变体形成不同形态,各种变体有助于科学家了解气候。

    Review
    ::回顾

    1. Describe how these depositional features form: moraine, drumlin, esker, and kettle lake.
      ::描述这些沉积特征是如何形成的:莫雷因、鼓林、埃斯克和茶壶湖。
    1. Why are varves important to scientists?
      ::为什么 varves 对科学家很重要?
    1. Why does the presence of glacial till mean there was a glacier in the area?
      ::为什么冰川的存在 意味着该地区有冰川?