The Layer of Earth
地层 I-18 / 018

Do you have an apple at home? Ask an adult to cut it open. What do you see? The apple has layers. The top layer is the peel. It is thin but tough and protects the fruit. The next layer is the fruit. It can be soft or hard and most of the apple is the fruit. The inside layer is the core. It is harder than the rest of the apple and protects the seeds that are in the center.

The earth is very much like the apple. It has four layers. The outer layer is the crust. It is solid rock. The rock is from 5 to 20 miles thick, and it's thicker underneath the continents. The next layer is called the mantle. It is the thickest layer, about 1,800 miles thick and made up of rock.

This rock may move because of the high temperature and great pressure found there. The third layer is the outer core. It is liquid, or melted iron. This layer is about 1,400 miles thick. The innermost layer is the inner core. It is made of iron and nickel. It is extremely hot, reaching temperatures of more than 9,000°F. This is a solid mass of rock and is about 800 miles thick.

Words and Phrases

layer [ˈleɪə(r)] 名 层，层次

peel [pi:l] 名 果皮；动 削皮

core [kɔ:(r)] 名 核心；果核

crust [krʌst] 名 地壳

mantle [ˈmæntl] 名 地幔（指位于地壳之下，地核之上的部分）

outer core 外核

inner core 内核

nickel [ˈnɪkl] 名 镍

Practice

Directions: Label the layer of the earth. Then answer the question.

1.________________________________________________________________________________________

2.________________________________________________________________________________________

3.________________________________________________________________________________________

4.________________________________________________________________________________________

5. Which layer of the earth do you think shows the most evidence of an earthquake?

________________________________________________________________________________________

译文

地层

你家里有苹果吗？请一位大人把它切开。你看到了什么？苹果是有层次的。最外层是果皮，它虽然薄却坚韧，起到保护果肉的作用。下一层则是果肉，果肉有的硬，有的软，苹果大部分都是果肉。里面那层则是果核，它是苹果最硬的部位，以此来保护苹果中央部位的种子。

地球非常像苹果，它分为四层。最外层叫地壳，它是一层坚硬岩石，厚达5到20英里（约8～32公里），在大陆下方则会更厚些。地壳下面是地幔，它是地球结构中最厚的层，厚度约达1,800英里（约2,900公里），地幔也是由岩石构成的。

由于高温及高压，地幔层会移动。第三层则是外核，它由液体或是熔化的铁构成。外核的厚度大约有1,400英里（约2,253公里）。地球最里层则是内核，它由铁和镍构成，内核温度很高，超过9,000华氏度（约4982.2摄氏度）。内核是由大量岩石构成的固体，大约有800英里（约1,287公里）厚。

练习

说明：标出地球的层次，然后回答问题。

1.________________________________________________________________________________________

2.________________________________________________________________________________________

3.________________________________________________________________________________________

4.________________________________________________________________________________________

5．你认为地球的哪一层最能显示出地震的迹象？

________________________________________________________________________________________