49 Earth's Changing Face-Low

Earth's Changing Face Written by Celeste Fraser

《地球的变化》作者:塞莱斯特·弗雷泽

Introduction "Mount Redoubt had recently erupted. When I arrived in Anchorage, Alaska, three days later, it was raining. The streets and sidewalks looked black. I realized it was raining volcanic ash!" That story was told by a teacher. Mount Redoubt is a volcano. Volcanoes are places where gases, ash, and lava spew out from beneath Earth's surface. Volcanoes are forces that create new features on Earth. Other forces, like water and wind, change existing features. Some changes happen quickly. Others take place very slowly. In this book, you will read about Earth's changing "face."

“棱堡火山最近爆发了。 三天后，当我到达阿拉斯加的安克雷奇时，天正在下雨。 街道和人行道看起来一片漆黑。 我意识到正在下火山灰!”那个故事是一位老师讲的。 棱堡山是一座火山。 火山是从地表以下喷出气体、火山灰和熔岩的地方。 火山是在地球上创造新特征的力量。 其他力量，如水和风，改变了现有的特征。 有些变化发生得很快。 其他的则发生得非常缓慢。 在这本书中，你将读到地球变化的“面貌”。

Earth's Structure To understand Earth's surface, you have to look deep inside it. Imagine a hard-boiled egg It has three layers: the eggshell, the white, and the yellow yolk inside. Earth has layers, too. They differ in thickness, temperature, and weight. The Crust The outer layer is called the crust. Unlike an eggshell, its thickness varies. It ranges from about 5 to 40 kilometers (3-30 mi.) The thickest crust is simply higher land. These are the landmasses where people live. We call the largest of these landmasses continents and the smaller ones islands. The thinnest part of the crust forms the floor of all the oceans.

要了解地球的表面，你必须深入观察它的内部。 想象一个煮熟的鸡蛋。它有三层:蛋壳、蛋黄和里面的黄色蛋黄。 地球也有层次。它们的厚度、温度和重量不同。 外层被称为地壳。 与蛋壳不同，它的厚度是不同的。 它的范围约为5至40公里(3-30英里)，最厚的地壳只是地势较高的地方。 这些是人们居住的大陆。 我们把这些大陆中最大的称为大陆，较小的称为岛屿。 地壳最薄的部分构成了所有海洋的底部。

The crust is not smooth like an eggshell. Instead, it is made up of uneven shapes. These different shapes are called landforms. Look at the collage of pictures on pages 22 and 23 to see some of Earth's many landforms. We will learn about the forces that created and shaped these landforms in the next section.

它的外壳不像蛋壳那么光滑。 相反，它是由不均匀的形状组成的。 这些不同的形状被称为地貌。 请看第22页和第23页的拼贴图，看看地球上的一些地貌。 在下一节中，我们将了解创造和塑造这些地貌的力量。

The Mantle Deeper inside Earth, temperatures get hotter. The layer underneath the crust is called the mantle. The rock there is in a semi-liquid state. The mantle which is very thick, makes up most of the planet. The Core Deeper still, at the very center of Earth, is the core. It consists of two layers—the outer core and the inner core. These layers are very different from one another. The outer core is liquid. It has a temperature of about 2200 degrees Celsius (4000°F). That's nearly as hot as the Sun's surface! The inner core is even hotter, about 5000 degrees Celsius (9000°F). It is a ball of solid metal. WOWSER! Because lava can be so hot—up to 1250°C (2000°F)—there's nothing people can do to stop it!

在地球内部，温度越来越高。 地壳下面的一层叫做地幔。 那里的岩石处于半液态。 地幔非常厚，构成了地球的大部分。 地核再深一点，在地球的正中心，是地核。 它由两层组成——外核和内核。 这些层之间非常不同。 外核是液态的。它的温度约为2200摄氏度(4000华氏度)。 这几乎和太阳表面一样热!内核甚至更热，约5000摄氏度(9000华氏度)。 它是一个实心金属球。 老古板!因为熔岩可以热到1250°C(2000°F)，人们无法阻止它!

Forces That Create Landforms Some landforms like mountains, are constantly being created. To understand how and why, we need to learn more about the inside of Earth. Moving Magma Moving Crust Like a cracked eggshell, Earth's crust is cracked. The pieces of crust are called plates. The plates move as fast as your fingernails grow—two to three inches a year! To understand why, picture a pot of thick soup. The hottest soup is at the bottom of the pot, nearest the heat source. The coolest soup is at the surface, farthest from the heat source.

形成地貌的力量像山脉这样的地貌是不断形成的。 为了了解如何以及为什么，我们需要更多地了解地球内部。 移动的岩浆移动的地壳就像破裂的蛋壳一样，地壳也破裂了。 这些地壳碎片被称为板块。 指甲板的移动速度和你指甲的生长速度一样快——每年两到三英寸!要理解其中的原因，想象一锅浓汤。 最热的汤在锅底，离热源最近的地方。 最冷的汤在离热源最远的表面。