英语听力：探索发现 2012-11-11 美洲大平原 American Serengeti—7

 The store of pollen¹ paints a picture of the plains of 13,000 years ago, a picture that looks very different from the open prairie grassland² of today. 

 

But why did this region look so different back then? The ice sheets to the north, although retreating 13,000 years ago, still dominated the climate here. It was much milder and wetter than today, ideal conditions for woodland to flourish. 

 

This is how much of the northern plains must have looked when the first people arrived. Not open prairies as it is now, but a parkland of trees and grassy³ meadows. 

 

This is a relic⁴ of those times. The Osage orange. Every autumn it produces these enormous fruits, huge numbers of them, more the size of great fruits than mere⁵ oranges. 

 

But there’s no animal alive today that's big enough to pick and eat them, so this bump of crop just rots. The Osage orange glory days are long gone. But its harvest was once an annual feast for many ice age animals, including mammoths. Fruit must have been a real treat for these grass eaters.

1 pollen   

n.[植]花粉

参考例句：

• Hummingbirds have discovered that nectar and pollen are very nutritious.蜂鸟发现花蜜和花粉是很有营养的。
• He developed an allergy to pollen.他对花粉过敏。

2 grassland   

n.牧场，草地，草原

参考例句：

• There is a reach of grassland in the distance.远处是连绵一片的草原。
• The snowstorm swept the vast expanse of grassland.暴风雪袭击了辽阔的草原。

3 grassy   

adj.盖满草的；长满草的

参考例句：

• They sat and had their lunch on a grassy hillside.他们坐在长满草的山坡上吃午饭。
• Cattle move freely across the grassy plain.牛群自由自在地走过草原。

4 relic   

n.神圣的遗物，遗迹，纪念物

参考例句：

• This stone axe is a relic of ancient times.这石斧是古代的遗物。
• He found himself thinking of the man as a relic from the past.他把这个男人看成是过去时代的人物。

5 mere   

adj.纯粹的；仅仅，只不过

参考例句：

• That is a mere repetition of what you said before.那不过是重复了你以前讲的话。
• It's a mere waste of time waiting any longer.再等下去纯粹是浪费时间。