What was the origin of the oil which now drives our motor-cars and aircraft? Scientists are confident about the formation of coa

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问题 What was the origin of the oil which now drives our motor-cars and aircraft? Scientists are confident about the formation of coal, but they do not seem so sure when asked about oil. They think that the oil under the surface of the earth originated in the distant past, and was formed from living things in the sea. Countless billions of minute sea creatures and plants lived and sank to the sea bed. They were covered with huge deposits of mud, and by processes of chemistry, pressure and temperature were changed through long ages into what we know as oil. For these creatures to become oil it was necessary that they should be imprisoned between layers of rock for an enormous length of time. The statement that oil originated in the sea is confirmed by a glance at a map showing the chief oilfields oi the world; very few of them are far distant from the oceans of today. In some places gas and oil come up to the surface of the sea from its bed. The rocks in which oil is found are of marine origin too. They are sedimentary rocks, rocks which were laid down by the action of water on the bed of the ocean. Almost always the remains of shells, and other proofs of sea life, are found close to the oil. A very common sedimentary rock is called shale, which is a soft rock and was obviously formed by being deposited on the sea bed. And where there is shale there is likely to be oil.
Geologists, scientists who study rocks, indicate the likely places to the oil drillers. In some cases oil comes out of the ground without any drilling at all and has been used for hundreds of years. In the island of Trinidad the oil is in the form of asphalt, a substance used for making roads. Sir Walter Raleigh visited the famous pitch lake of Trinidad in 1595; it is said to contain nine thousand million tons of asphalt. There are probably huge quantities of crude oil beneath the surface.

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答案 我们现在用来开汽车、开飞机的油是怎么来的?科学家们确信煤炭是怎么形成的,但若问到油是怎么形成的,他们似乎就不那么确定了。他们认为地表下的石油形成于远古时期,是由海里的生物形成的。不计其数的亿万微小的海洋生物和植物下沉到海床上,上面覆盖着沉积的泥沙,通过化学、压力以及温度的作用,经过很长时间的变化,形成了我们所说的石油。这些生物必须在层层的岩石之间密封起来,经过极长的一段时间才能形成石油。只要看一下世界主要油田的地图,就可以证实石油是来源于海洋的说法,而且大部分都是位于现在的近海。有些地方的石油和天然气都上浮到了海面之上。发现石油的岩石也是海里形成的,这些都是沉积岩,由于海水的作用,它们压结在了海床之上。在石油的附近总能找到贝壳的遗骸或是其他海洋生命的迹象。有一种普通的沉积岩叫页岩,这是一种松软的岩石,很明显是海床沉积形成的。有页岩的地方就可能会有石油。 地质学家是研究岩石的科学家,他们可以为钻探石油的人指出哪里可能会有石油。在有些地方,石油根本不用钻探就冒了出来,而且已经使用了上百年。在特立尼达岛,石油是以沥青的形式出现的,沥青可以用来铺路。1595年,沃尔特?雷利爵士参观了特立尼达岛上著名的沥青湖,据说那里面有90亿吨沥青。湖面之下可能有大量的原油。

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