英语听力：自然百科 黄石公园的夏天 Yellowstone—4

 Clues to why the herds¹ are drawn² to the Yellowstone plateau lie in its deep and unique history.

 

This plateau is the created bowl of a huge sleeping volcano. And melting rock below the surface still pushes the land up to the cold of high altitude.

 

But it has not been the only force to shape the land.

 

Millennia³ ago, the volcano was covered by an ice sheet thousands of feet deep.

 

The few glaciers⁴ that border Yellowstone are an echo of a time when ice scarred and smoothed the entire plateau.

 

When these great ice sheets retreated, they left pulverized⁵ rocks in their wake, the foundation for fertile soil and some of the richest natural grasslands⁶ in America.

 

But in May this year, in the heart of Yellowstone, that grass is still beneath thick snow - something this ground squirrel was clearly not expecting.

 

But as the sun's strength returns, spring bulbs start to push through the late snow - at last a sign that winter is losing its grip.

 

Bluebirds, too delicate to survive deep winter here, now return to take advantage of the fist hatch of stoneflies from a thawing⁷ river.

1 herds   

兽群( herd的名词复数 )； 牧群； 人群； 群众

参考例句：

• Regularly at daybreak they drive their herds to the pasture. 每天天一亮他们就把牲畜赶到草场上去。
• There we saw herds of cows grazing on the pasture. 我们在那里看到一群群的牛在草地上吃草。

2 drawn   

v.拖，拉，拔出；adj.憔悴的，紧张的

参考例句：

• All the characters in the story are drawn from life.故事中的所有人物都取材于生活。
• Her gaze was drawn irresistibly to the scene outside.她的目光禁不住被外面的风景所吸引。

3 millennia   

n.一千年，千禧年

参考例句：

• For two millennia, exogamy was a major transgression for Jews. 两千年来，异族通婚一直是犹太人的一大禁忌。
• In the course of millennia, the dinosaurs died out. 在几千年的时间里，恐龙逐渐死绝了。

4 glaciers   

冰河，冰川( glacier的名词复数 )

参考例句：

• Glaciers gouged out valleys from the hills. 冰川把丘陵地带冲出一条条山谷。
• It has ice and snow glaciers, rainforests and beautiful mountains. 既有冰川，又有雨林和秀丽的山峰。 来自英语晨读30分（高一）

5 pulverized   

adj.[医]雾化的，粉末状的v.将…弄碎( pulverize的过去式和过去分词 )；将…弄成粉末或尘埃；摧毁；粉碎

参考例句：

• We pulverized the opposition. 我们彻底击败了对手。
• He pulverized the opposition with the force of his oratory. 他能言善辩把对方驳得体无完肤。 来自辞典例句

6 grasslands   

n.草原，牧场( grassland的名词复数 )

参考例句：

• Songs were heard ringing loud and clear over the grasslands. 草原上扬起清亮激越的歌声。 来自《现代汉英综合大词典》
• Grasslands have been broken and planted to wheat. 草原已经开垦出来，种上了小麦。 来自《简明英汉词典》

7 thawing   

n.熔化，融化v.（气候）解冻( thaw的现在分词 )；（态度、感情等）缓和；（冰、雪及冷冻食物）溶化；软化

参考例句：

• The ice is thawing. 冰在融化。 来自《现代英汉综合大词典》
• It had been snowing and thawing and the streets were sloppy. 天一直在下雪，雪又一直在融化，街上泥泞不堪。 来自英汉文学 - 嘉莉妹妹