万物简史 第614期:冰河时代(11)

The cause of ice ages, Koppen decided¹, is to be found in cool summers, not brutal² winters. If summers are too cool to melt all the snow that falls on a given area, more incoming sunlight is bounced back by the reflective surface, exacerbating³ the cooling effect and encouraging yet more snow to fall. The consequence would tend to be self-perpetuating. As snow accumulated into an ice sheet, the region would grow cooler, prompting more ice to accumulate. As the glaciologist Gwen Schultz has noted⁴: "It is not necessarily the amount of snow that causes ice sheets but the fact that snow, however little, lasts." It is thought that an ice age could start from a single unseasonal summer. The leftover⁵ snow reflects heat and exacerbates⁶ the chilling effect. "The process is self-enlarging, unstoppable, and once the ice is really growing it moves," says McPhee. You have advancing glaciers⁷ and an ice age.

柯本认为，产生冰川期的原因是因为凉快的夏季，而不是严寒的冬季。如果在某一地区夏季非常凉快，射来的阳光就会被地表反射，这样就加剧了寒冷的程度，使得更多的雪降下来，结果往往是地表的冰雪永久化。随着积雪成冰盖，整个地区就会更加寒冷，以致冰雪越积越多了。正如冰川学家格文·舒尔茨所说的那样：“冰盖的产生并不取决于下了多少的雪，而是取决于有多少未融化的雪——不管多么少。”冰川期被认为开始于某个季节反常的夏天，未融化的雪反射了热量，加剧了寒冷的效果，麦克菲说：“这是一个不断自我扩大的过程，而冰盖一旦形成，它就开始移动。”这样，就有了移动的冰川，也就进入到了一个冰川时代。

In the 1950s, because of imperfect dating technology, scientists were unable to correlate Milankovitch's carefully worked-out cycles with the supposed dates of ice ages as then perceived, and so Milankovitch and his calculations increasingly fell out of favor. He died in 1958, unable to prove that his cycles were correct. By this time, write John and Mary Gribbin, "you would have been hard pressed to find a geologist⁸ or meteorologist who regarded the model as being anything more than an historical curiosity." Not until the 1970s and the refinement⁹ of a potassium-argon method for dating ancient seafloor sediments¹⁰ were his theories finally vindicated¹¹.

20世纪50年代，由于检测年代技术的不完善，科学家们并没有能把当时所掌握的有关冰川期的数据与米兰柯维契精确计算出来的周期进行对比，因此，米兰柯维契及其计算结果越来越不吃香。直到1958年去世时，米兰柯维契知未能证明其周期的正确性。到了这个时候，用一部记述该时期的史书里的话来说：“你会迫切需要找到一位认为那个计算结果不仅仅是一个古董地质学家或气象学家。”直到20世纪70年代，随着用于确定古代海底沉淀物的年代的钾氩测年方法的改善，米兰柯维契的理论才最终得以确证。

1 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

2 brutal   

adj.残忍的，野蛮的，不讲理的

参考例句：

• She has to face the brutal reality.她不得不去面对冷酷的现实。
• They're brutal people behind their civilised veneer.他们表面上温文有礼，骨子里却是野蛮残忍。

3 exacerbating   

v.使恶化，使加重( exacerbate的现在分词 )

参考例句：

• This pedagogical understretch is exacerbating social inequalities. 这种教学张力不足加重了社会不平等。 来自互联网
• High fertilizer prices are exacerbating the problem. 高涨的肥料价格更加加剧了问题的恶化。 来自互联网

4 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

5 leftover   

n.剩货，残留物，剩饭；adj.残余的

参考例句：

• These narrow roads are a leftover from the days of horse-drawn carriages.这些小道是从马车时代沿用下来的。
• Wonder if that bakery lets us take leftover home.不知道那家糕饼店会不会让我们把卖剩的带回家。

6 exacerbates   

n.使恶化，使加重( exacerbate的名词复数 )v.使恶化，使加重( exacerbate的第三人称单数 )

参考例句：

• Stripping the land in these ways allows faster surface runoff and exacerbates flooding. 这些做法终将使土地裸露、地表径流加快，从而加重了洪水的威胁。 来自辞典例句
• This policy exacerbates the gap between rich and poor. 这项政策加剧了贫富差距。 来自互联网

7 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）

8 geologist   

n.地质学家

参考例句：

• The geologist found many uncovered fossils in the valley.在那山谷里，地质学家发现了许多裸露的化石。
• He was a geologist,rated by his cronies as the best in the business.他是一位地质学家，被他的老朋友们看做是这门行当中最好的一位。

9 refinement   

n.文雅；高尚；精美；精制；精炼

参考例句：

• Sally is a woman of great refinement and beauty. 莎莉是个温文尔雅又很漂亮的女士。
• Good manners and correct speech are marks of refinement.彬彬有礼和谈吐得体是文雅的标志。

10 sediments   

沉淀物( sediment的名词复数 )； 沉积物

参考例句：

• When deposited, 70-80% of the volume of muddy sediments may be water. 泥质沉积物沉积后，体积的70-80％是水。
• Oligocene erosion had truncated the sediments draped over the dome. 覆盖于穹丘上的沉积岩为渐新世侵蚀所截削。

11 vindicated   

v.澄清（某人/某事物）受到的责难或嫌疑( vindicate的过去式和过去分词 )；表明或证明（所争辩的事物）属实、正当、有效等；维护

参考例句：

• I have every confidence that this decision will be fully vindicated. 我完全相信这一决定的正确性将得到充分证明。
• Subsequent events vindicated the policy. 后来的事实证明那政策是对的。 来自《简明英汉词典》