在中学生物学课本中,有关生物进化的章节都附有一个“地质年代表”。在“距今年数”栏目里开列出了各地质时代(代、纪、世等)距离现代的年数。如中生代从距今2亿2千5百万年开始等等。有的学生向教师提出,这些年代是如何计算出来的?回答这个问题,还得从放射性同位素谈起。因为表里所列出的年代是地层形成的绝对年龄。它是根据放射性元素衰变规律计算出来的。 In the biology textbooks for secondary schools, a chapter on “Geological Chronology” is attached to chapters on the evolution of biology. In the “year from now” section lists out the geological era (generation, discipline, world, etc.) from the modern years. As the Mesozoic dating back to 250 million years ago and so on. Some students put forward to teachers how these ages were calculated. To answer this question, we still have to talk about radioisotopes. Because the age listed in the table is the formation of the absolute age of strata. It is based on the decay of radioactive elements calculated.