英语听力：自然百科 墨西哥湖泊与生命的启示

 

 The small town of Cuatro Cienegas in northern Mexico is an oasis¹ (绿洲) in the Chihuahuan desert. It’ s a valley that holds an example of what some believe is the one of the first human footprints in the Americas(美洲大陆以及附近岛屿) along with cave paintings produced by the first people who walked through this valley.

These rock paintings were made with iron oxides(铁的氧化物), some plant extracts and even with some drops of blood. These have their origins in the first settlers of America ten thousand years ago.

Cuatro Cienegas fosters a unique ecosystem² from prehistoric³ times and the research done here has enlightened scientists and historians.

We have tracked only the history of organisms when the sea existed here 200 million years ago, but also the very same environmental conditions as the ones when life began on earth 35 to 38 hundred million years ago. So this is a time machine, and it is the only one we have on earth.

To find the secrets of the valley, scientists carried out experiments in the four large ponds for which the areas named. Samples of fossilized algae(海藻), known as stromatolites(叠层石), are taken back to laboratory so scientists can grow the microorganisms they discovered in the wild.

By extracting DNA⁴ from stromatolite, the scientists hope to gain insight into the effects and causes of global warming. Reportedly results have already revealed how marine⁵ fish and turtles adapted to live in fresh water.

Each one of these wells has a unique history just as the Galapagos Islands(加拉帕哥斯群岛，位于厄瓜多尔西部，拥有多种独特生物，达尔文在岛上的考察成果成为进化论的重要依据). What we are trying todecode here is the origin of the species that Darwin overlooked--the origin of the small species.

The American space agency NASA also has a special interest in Cuatro Cienegas.

Microbial(微生物的) life here dominates and if we are going to find life on Mars it’ll probably be microbial life, so if we understand life here in this place we might be able to understand how to find it on Mars.

Despite the fact that UNESCO is calling for a Cuatro Cienegas’s conservation, its future is not secure. Irrigation for agriculture and cattle grazing, as well as poorly managed development in tourism, all threaten this important area. This makes responsible ecotourism all the more(更加，加强语气) important to the town’s people. The local government insists it’s trying to strike a balance between the needs of the residents and the need to preserve the region for future generations.

1 oasis   

n.（沙漠中的）绿洲，宜人的地方

参考例句：

• They stopped for the night at an oasis.他们在沙漠中的绿洲停下来过夜。
• The town was an oasis of prosperity in a desert of poverty.该镇是贫穷荒漠中的一块繁荣的“绿洲”。

2 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。

3 prehistoric   

adj.（有记载的）历史以前的，史前的，古老的

参考例句：

• They have found prehistoric remains.他们发现了史前遗迹。
• It was rather like an exhibition of prehistoric electronic equipment.这儿倒像是在展览古老的电子设备。

4 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

5 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
• When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。