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地球有46亿年的历史了,在这漫长的历史中,她一直在变化着,只不过有时大,有时小,把大的变化称为巨变也未尝不可。纵观地球历史,至少有8次巨变。第一次巨变,发生在距今40亿年,地球由最初高温熔融状态的红色火球逐渐冷却,密度大的铁、镍逐渐沉到中心而成高温固体状的地内核。密度较小点的高温液体状的硫、硅形成了地外核。而密度再小的氧化铁、氧化镁、二氧化硅、三氧化二铝在下;橄榄石、正辉石在中;上为高温熔融的软流层,这三圈形成了地幔层:地幔层之上才是硬的地壳。
Earth has a history of 4.6 billion years. In this long history, she has been changing, but sometimes big and sometimes small. It is also not a bad idea that big changes are called tremendous changes. Looking at the history of the earth, at least 8 changes. The first major change took place 4 billion years ago. The Earth gradually cooled from the red fireball in the initial high-temperature molten state. The dense iron and nickel were gradually sunk into the center to form the high-temperature solid core. Smaller points of high temperature liquid sulfur, silicon formed to the outer core. The density of iron oxide, magnesium oxide, silicon dioxide, aluminum oxide in the next; olivine, pyroxene in; on the high temperature molten asthenosphere, the three laps formed a mantle layer: the mantle layer It is hard crust.