重力侵蚀和沉积

Lesson Objectives
::经验教训目标

• Identify causes and effects of landslides and mudslides.
  ::查明山崩和泥石流的原因和影响。

• Explain how slump and creep occur.
  ::解释一下如何出现贫民窟和爬行。

Lesson Vocabulary
::词汇表课程

• creep
  ::缩进( Screit)

• landslide
  ::山体滑坡

• mass movement
  ::大规模移动

• mudslide
  ::泥石流

• slump
  ::贫民窟

Introduction
::导言

Gravity is the indirect cause of most erosion. Gravity is responsible for erosion by flowing water and glaciers. That's because gravity pulls water and ice downhill. These are ways gravity causes erosion indirectly. Gravity also causes erosion directly. Gravity can pull soil, mud, and rocks down cliffs and hillsides. This type of erosion and deposition is called  mass movement . It may happen suddenly, or it may occur very slowly. It may take many years.
::重力是大部分侵蚀的间接原因。 重力是水流和冰川侵蚀的原因。 这是因为重力拉动水和冰下坡。 这些是重力间接导致侵蚀的方式。 重力还直接导致侵蚀。 重力可以将土壤、 泥土和岩石拖到悬崖和山坡下。 这种类型的侵蚀和沉降被称为大规模移动。 它可能突然发生, 也可能非常缓慢地发生。 它可能需要许多年时间 。

Landslides and Mudslides
::滑石和泥石流

The most destructive types of mass movement are landslides and mudslides. Both occur suddenly. If you are in their path, they can be deadly. 
::最具破坏性的大规模流动类型是山崩和泥石流,两者都突然发生。如果你在他们的道路上,它们可能是致命的。

Landslides
::滑石

A  landslide  happens when a large amount of soil and rock suddenly fall. The rock and soil fall down a slope because of gravity. You can see an example in  Figure   . A landslide can be very destructive. It may bury, or carry away, entire villages.
::当大量土壤和岩石突然倒塌时,就会发生塌方。岩石和土壤会因重力而跌落坡度。您可以看到图中的一个例子。山体滑块可能会破坏力很大。它可能埋没或带走整个村庄。

A landslide is more likely if the soil has become wet from heavy rains. The wet soil becomes slippery and heavy. 
::如果土壤因暴雨而变得湿润,滑坡的可能性更大,湿土变得滑重。

Earthquakes can also cause landslides. In these cases, the ground does not need to be wet and slippery. It is the shaking of the ground that causes the soil and rock to break loose and move. Sometimes, debris from landslides falls into water. When this happens, it may cause a huge wave called a tsunami.
::地震也可能引发山崩。 在这些情况下,地面不需要湿滑。正是土壤和岩石的摇晃导致了土壤和岩石的松散和移动。 有时,山崩产生的碎片会掉进水中。 发生这种情况时,可能会引发一场称为海啸的巨浪。

Mudslides
::滑石

A  mudslide  is the sudden flow of mud down a slope. Mudslides occur where the soil is mostly clay. Clay soil is composed of very small particles. The space between these particles is able to hold a lot of water. Wet clay forms very slippery mud that slides easily. You can see an example of a mudslide in  Figure   .
::泥浆滑坡是泥浆从斜坡上突然流出。泥浆滑坡发生在土壤大多为粘土的地方。 Clay 土壤由非常小的微粒组成。 这些微粒之间的空间可以容纳大量水。 湿泥浆形成非常滑滑的泥浆,很容易滑动。 您可以在图中看到泥浆滑坡的例子 。

Other Types of Mass Movement
::其他种类的大规模迁徙

Two other types of mass movement are slump and creep. Both may move a lot of soil and rock. However, they usually aren't as destructive as landslides and mudslides. 
::两种其他的大规模迁移形式是暴跌和爬虫。两者都可能会移动大量的土壤和岩石。然而,它们通常不会像山崩和泥石流那样具有破坏性。

Slump
::贫民窟

Slump  is the sudden movement of large blocks of rock and soil down a slope. You can see how it happens in  Figure   . All the material moves together in big chunks. Slump may be caused by a layer of slippery, wet clay. The wet clay may be under the rock and soil on a hillside. Or it may occur when a river undercuts a slope. Slump leaves behind crescent-shaped scars on the hillside.
::贫民窟是大块岩石和土壤在斜坡上的突然移动。 您可以在图中看到它是如何发生的。 所有物质在大块块中一起移动。 贫民窟可能是滑滑湿粘土层造成的。 湿粘土可能在山坡的岩石和土壤下。 或者, 当河流侵蚀斜坡时可能发生。 贫民窟在山坡上留下新月形的疤痕。

Creep
::缩缩

Creep  is the very slow movement of rock and soil down a hillside. Creep occurs so slowly you can't see it happening. You can only see the effects of creep after years of movement. This is illustrated in  Figure   . The slowly moving ground causes everything to move with it. This includes trees, fence posts, and other structures on the surface. 
::克里普是岩石和土壤在山坡上的缓慢移动。 克里普发生得如此缓慢, 你看不到它发生。 您只能看到经过多年移动后爬行的影响。 图中说明了这一点。 缓慢移动的地面导致一切随地移动。 这包括树木、 栅栏柱和表面的其他结构 。

Creep usually takes place where the ground freezes and thaws frequently. Soil and rock particles are lifted up when the ground freezes. When the ground thaws, the particles settle down again. Each time they settle down, they move a tiny bit farther down the slope because of gravity.
::土质和岩质粒子通常在地面冷却和解冻频繁的地方发生。 当地面冷却时,土壤和岩石粒子会被提升。 当地面解冻时,粒子会再次沉降。 每次它们安定下来时,它们会因为重力而向斜坡移动一小步。

Lesson Summary
::经验教训摘要

• Gravity can pull soil, mud, and rocks down cliffs and hillsides. This is called mass movement.
  ::引力可以拉动土壤、泥土和岩石 从悬崖和山坡下。这叫做大规模移动。

• The most destructive types of mass movement are landslides and mudslides. They occur suddenly. They generally have little warning before they happen. They engulf everything in their path.
  ::最具破坏性的大规模迁移类型是山崩和泥石流,它们突然发生。它们通常在它们发生之前没有什么警告,它们吞没了它们道路上的一切。

• Two other types of mass movement are slump and creep. They usually aren't as destructive as landslides and mudslides.
  ::两种其他的大规模迁移是暴跌和爬行。它们通常不会像山崩和泥石流那样具有破坏性。

• Slump is the sudden movement of large blocks of rock and soil down a slope.
  ::贫民窟是一大块岩石和土壤突然从斜坡向下移动。

• Creep is the very slow movement of rock and soil down a slope. It causes trees, fence posts, and other structures to tilt downhill.
  ::岩浆和土壤在斜坡下移动非常缓慢,造成树木、栅栏柱和其他结构向下倾斜。

Lesson Review Questions
::经验回顾问题

Recall
::回顾

1. Define mass movement.
   ::定义大众流动。

1. List four types of mass movement.
   ::列出四类大规模流动。

1. What is a landslide?
   ::什么是山崩?

1. What factors increase the chances of landslides occurring?
   ::哪些因素增加了山崩发生的可能性?

1. What type of soil forms mudslides?
   ::哪种土壤形成泥石流?

Apply Concepts
::应用概念

6. Assume you are riding in a car down a road or street. Suddenly, you see evidence of creep. Describe it. 
   ::假设你在路上或街上开着汽车 突然间你看到了爬行的证据 描述一下

Think Critically
::仔细仔细思考

7. Relate earthquakes to mass movement.
   ::将地震与大规模移动联系起来。

7. Compare and contrast slump and creep.
   ::比较和对比 贫民窟和爬虫。

Points to Consider
::需要考虑的要点

Erosion and deposition are always changing Earth's surface.
::侵蚀和沉降总是在改变地球表面

• Do you think that the same forces that cause erosion today — moving water, wind, ice, and gravity — were also at work in the past?
  ::你认为今天造成侵蚀的同样力量——移动水、风、冰和重力——过去也在起作用吗?

• How might observations of erosion and deposition today help us understand Earth's history?
  ::今天对侵蚀和沉积的观察如何帮助我们了解地球的历史?