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地质年代中为什么只有第三、四纪,而没有第一、二纪?原来,早期的地史学家,曾把地球的历史分为第一、第二、第三和第四纪.第一纪、第二纪分别相当于现在地质年代表中的古生代、中生代.后来,随着地史学研究工作的深入,发现第一、二纪这两个时期的地层很厚,化石种类很多,有多次大的地壳运动(大的沉积旋回),故将第一纪分为六个纪,改名古生代;把第二纪分为三个
Why the geological era only the third and the fourth century, but no first, second? The original, historians of the early, once the earth’s history is divided into first, second, third and quaternary. , Respectively, which correspond to the Paleozoic and Mesozoic Mesozoic in the current geologic time series.Later, with the deepening of geo-history research, we found that the strata in the two periods of the first and second centuries are very thick with many kinds of fossils, Of the crustal movement (large sedimentary cycle), so the first division is divided into six disciplines, renamed the Paleozoic; the second division is divided into three