英语听力：自然百科 地球力场 Earth's Force Field—14

By analyzing¹ different samples of lava², Herrero / Bervera  has built up a picture of how the filed has changed since long before humans were around.

 

 

 

They are actually the recorders of the Earth's magnetic field in hundreds of years, thousands of years, and this is what we need actually to know something about the Earth's magnetic filed. 

 

 

 

 

 

Lower layers of rock take Herrero Bervera progressively further back in time. 

 

 

 

To unlock the information, he takes a sample of the ancient lava, as well / he is showing how the field strength has changed, the sample will also reveal another vital piece of information. He carefully notes the sample's exact location.

 

 

 

And we would, we're going to measure it, demand the decision of the sample we collected in the field. 

 

 

 

Back at the lab, he analyses it using a magnetometer like a pottery³, lava contains / magnetite. When it cools, particles of magnetite lining⁴ up with the Earth's magnetic field like tiny compass needles, recording⁵ both its strength and its direction. In this sample, the magnetite lines with today's magnetic north. 

 

 

 

This sample wasn't placed in the past 700,000 years when the field was actually gluttonized by a normal polarity . 

 

 

 

But in old samples, they discover something incredible. The magnetic particles point South rather than North. They date back to a time when the magnetic field polarity was the opposite of today's.

 

 

 

There was a reversal actually recorded by these lava floors. I will be actually / able to see a sequence of points that are actually defining the behavior or the evolution of the magnetic field from the one polarity to the other polarity.

1 analyzing   

v.分析；分析( analyze的现在分词 )；分解；解释；对…进行心理分析n.分析

参考例句：

• Analyzing the date of some socialist countries presents even greater problem s. 分析某些社会主义国家的统计数据，暴露出的问题甚至更大。 来自辞典例句
• He undoubtedly was not far off the mark in analyzing its predictions. 当然，他对其预测所作的分析倒也八九不离十。 来自辞典例句

2 lava   

n.熔岩，火山岩

参考例句：

• The lava flowed down the sides of the volcano.熔岩沿火山坡面涌流而下。
• His anger spilled out like lava.他的愤怒像火山爆发似的迸发出来。

3 pottery   

n.陶器，陶器场

参考例句：

• My sister likes to learn art pottery in her spare time.我妹妹喜欢在空余时间学习陶艺。
• The pottery was left to bake in the hot sun.陶器放在外面让炎热的太阳烘晒焙干。

4 lining   

n.衬里，衬料

参考例句：

• The lining of my coat is torn.我的外套衬里破了。
• Moss makes an attractive lining to wire baskets.用苔藓垫在铁丝篮里很漂亮。

5 recording   

n.录音，记录

参考例句：

• How long will the recording of the song take?录下这首歌得花多少时间？
• I want to play you a recording of the rehearsal.我想给你放一下彩排的录像。