A QUARRY（采石场）
1.What is the oldest thing you have seen？One boy thinks it is a church，for he has seen a date on one which tells that it was built hundreds of years ago.
2.A girl thinks that an oak-tree which she has seen is older still，for her grandfather says he has read that it was growing a thousand years ago.
3.But what is that hard lump which Tommy has in his pocket？It is a stone which he picked up，because it had a curious look.
4.Well，it does not matter much about the curious look，but any common stone you find is almost certain to be the oldest thing you will ever see.The age of most stones goes back many thousands of years.
5.The stone which Tommy has found is called sandstone.It is made of little round grains of sand.Thousands and thousands of years ago these little grains of sand were lying loose on some sea-beach.Since then they have been pressed together so hard and for so long a time that they now form a sandstone rock.
6.But these grains of sand were themselves only broken bits of a still older rock.They must be many thousands of years older than the stone which has been formed out of them.
7.If we break up a great many lumps of sandstone，we shall be almost sure to find in some of them the shells of creatures that lived on the old sea-beach.Such old shells found in the rocks are called fossils.
8.Another kind of rock in which many fossils are found is called limestone.A drop of acid or of strongvinegar①will tell you whether a stoneis limestone or not.
FOSSILS IN LIMESTONE
（石灰岩里的化石）
9.As soon as the acid touches the limestone，it begins to fizz and to bubble.The acid causes a little of the limestone to dissolve，and a gas is formed，which escapes in small bubbles.
10.Clay is also a rock；and when it has been pressed a great deal，it is called shale.Shale splits very easily.
11.Some stones are made up of a great many little bits with flat shining sides and sharp corners，called crystals.Granite②is a rock of this kind.Such stones were long ago heated inside theearth till they melted，and then，as they cooled，the crystals were formed.
①Vinegar，a sour liquid got from wine，beer，etc.，used as a relish for food.
②Granite，a hard rock of a grey or reddish colour made up of grains of various substances.
12.Granite is a very pretty rock.Pillars made of polished①granite are often used in public buildings.No fossils are ever found in granite.If there ever were any in it，they were destroyed when the rock was melted.
13.There are great granite quarries②in Cornwall③and inScotland.A soft white limestone forms the chalk hills of the south-east and the east of England；and a hard limestone forms many of the hills in the north of England.
SUMMARY
Sandstone is made up of little round grains of sand which，thousands of years ago，were lying loose on some sea-beach.These grains of sand were themselves broken bits of a still older rock.Shells called fossils are sometimes found in lumps of sandstone，and more commonly in limestone.Shale is a kind of rock that has been formed from clay.Granite is made up of a great number of little bits with sharp corners，called crystals.
【中文阅读】
1．小朋友，你见过的最古老的东西是什么？有个男孩子觉得是教堂，因为他见过一所教堂（的石头上）刻着一个日期，说这所教堂是好几百年以前建造的。
2．有个女孩觉得，她见过的一棵橡树更古老，因为她爷爷说，他在书上看到过，这棵橡树在一千年前就已经有了。
3．不过，汤米口袋里的那个硬块儿是什么东西呢？那是一块他捡来的石头，因为他觉得样子很奇怪。
4．奇怪的样子倒没有什么关系，但是，你找到的任何平常的石头，几乎都肯定是你能见到的最古老的东西。大多数石头的年纪都有成千上万岁了。①①Polished，made smooth and glossy by rubbing.
②Quarries，places where stones are dug or cut.
③Cornwall，a county in the southwest of England.
5．汤米找到的这种石头，名叫“砂岩”（sandstone），是小小的圆形沙粒构成的。千万年前，这些沙子是散布在一些海岸上的，但是后来，这些沙子用极大的力量挤在一起，挤了很久，最后就形成了砂岩。
6．但是，这些沙粒，本身又是更古老的石头破碎形成的。这种石头，比沙粒形成的砂岩，还要古老成千上万年呢！
7．如果我们将很多块砂岩弄碎，几乎肯定会在一些砂岩里面，找到很久以前在海滩上生活的动物的甲壳。这些从岩石中找到的古老甲壳，名叫“化石”（fossil）。②8．另外一种含有很多化石的石头，叫做“石灰岩”也叫“灰岩”
（limestone）。想分辨一块石头是不是石灰岩，只要用一滴酸液或者一滴浓醋就行了。
9．酸液一落到石灰岩的表面，就会冒气泡，发出嘶嘶的声音。酸液“溶解”了一点儿石灰岩，形成一种气体，变成小气泡冒出来。③10．粘土也是一种石头，经过大力挤压之后，叫做“页岩”（shale）。页岩可以很容易地分成很多片。
11．有些石头，是很多很多表面平整闪光、棱角锋利的小块组成的，这些小块叫做“晶体”（crystal）。这样的石头，是很久以前在地下被加热到熔化，然后又冷却的。冷却的时候，就形成了这些晶体。
12．花岗岩是一种十分漂亮的石头，英国的公共建筑，经常用打磨过的花岗岩做柱子。花岗岩里，从来没有找到过化石，如果有过化石，也在花岗岩熔化的时候毁坏了。④13．英国的康沃尔郡和苏格兰王国，都有大型的采石场。英格兰东南部和东部，有很多白垩的小山，是一种软质白色石灰岩构成的；英国北部则有很多小山，是硬质的石灰岩构成的。
译注
①“成千上万”（many thousands of years）这句话太保守了。地球的年龄一般认为是46亿岁。最早的石头，从地球形成的初期，就没有被熔化和侵蚀过，可想而知，这种石头只有极少数暴露在地表。1999年的纪录是在加拿大西北部发现的艾加斯塔片麻岩（Acasta Gneiss），年龄大约40.31亿年，近年来又有报告说在加拿大北部发现了大约有38-42.8亿年的角闪岩（amphibolite）和辉绿岩（diabase）。有意思的是，1971年，美国的阿波罗15号探测器从月球带回来的“起源石”（The Genesis Rock），已经有44.6亿年的历史了，比地球上发现的还要古老。
②前面的课文里我们也见到过化石，还记得是哪里吗？
③从化学上说是这样的：石灰岩的主要成分是碳酸钙，与酸反应生成二氧化碳，变成气泡。
④花岗岩的英语granite，来自拉丁语的granum--“谷粒”或“颗粒”，因为花岗岩看上去很像一颗颗的矿物颗粒组成的。汉语“花岗岩”则来自近代日语，“花”代表美丽的斑纹，“岗”相当于“刚”，代表坚硬。现代，花岗岩依然是重要的建筑材料。它在全世界分布很广，中国的土地有9%都是花岗岩构成的。但是，红色和绿色的花岗岩有可能带有放射性，做装修材料的时候要注意检测。有趣的是，少数的花岗岩有一种“锰华”现象，是水中的矿物质“锰铁”渗透到石头中，发生化学反应的结果，看上去很像植物化石，但不是植物。
A LUMP OF COAL