新概念英語(yǔ)第四冊(cè)(含lrc文本)Lesson 26 The past life of the earth

[ti:δ?] [ar:] [al:] [by:https://www.lrc.com.cn] [00:01.77]Lesson 26 [00:03.99]The past life of the earth [00:11.42]What is the main condition for the preservation of the remains of any living creature [00:19.67]It is animals and plants which lived in or near water [00:23.56]whose remains are most likely to be preserved, [00:26.54]for one of the necessary conditions of preservation is quick burial, [00:31.62]and it is only in the seas and rivers, and sometimes lakes, [00:35.79]where mud and silt have been continuously deposited, [00:39.34]that bodies and the like can be rapidly covered over and preserved. [00:45.03]But even in the most favourable circumstances [00:47.76]only a small fraction of the creatures that die are preserved in this way [00:52.70]before decay sets in or,even more likely, before scavengers eat them. [00:58.75]After all,all living creatures live by feeding on something else, [01:03.74]whether it be plant or animal,dead or alive, [01:07.49]and it is only by chance that such a fate is avoided. [01:12.59]The remains of plants and animals that lived on land are much more rarely preserved, [01:18.04]for there is seldom anything to cover them over. [01:22.05]When you think of the innumerable birds that one sees flying about, [01:26.30]not to mention the equally numerous small animals like field mice and voles [01:31.70]which you do not see, [01:33.33]it is very rarely that one comes across a dead body,except,of course,on the roads. [01:40.52]They decompose and are quickly destroyed by the weather or eaten by some other creature [01:47.95]It is almost always due to some very special circumstances [01:51.95]that traces of land animals survive, [01:54.75]as by falling into inaccessible caves,or into an ice crevasse, [02:01.47]like the Siberian mammoths, [02:03.60]when the whole animal is sometimes preserved,as in a refrigerator. [02:09.22]This is what happened to the famous Beresovka mammoth [02:13.28]which was found preserved and in good condition. [02:17.02]In his mouth were the remains of fir trees-- [02:20.24]the last meal that he had before he fell into the crevasse and broke his back. [02:25.50]The mammoth has now been restored in the Palaeontological Muse-um in St.Petersburg. [02:32.06]Other animals were trapped in tar pits, [02:34.65]like the elephants,sabre-toothed cats,and numerous other creatures [02:39.41]that are found at Rancho la Brea,which is now just a suburb of Los Angeles. [02:45.29]Apparently what happened was that water collected on these tar pits [02:50.04]and the bigger animals like the elephants [02:52.74]ventured out on to the apparently firm surface to drink, [02:56.53]and were promptly bogged in the tar. [02:59.77]And then,when they were dead,the carnivores, [03:03.21]like the sabretoothed cats and the giant wolves, [03:06.75]came out to feed and suffered exactly the same fate. [03:11.10]There are also endless numbers of birds in the tar as well.

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