>为什么我们使用如果他们的陨石撞击地球形成后吗?* * * *简短的回答:因为陨石形成的地球和太阳系的其他部分。长* * * *回答:地球一起形成太阳系的其他部分和陨石大约45亿年前。当陨石落在地球上,你把它们捡起来,你可以约会的时间形成。你说:为什么我们使用如果他们的陨石撞击地球形成后吗?你必须区分陨石形成的时间和时间,它们撞击地球。如果我在你抛出一个陨石,日期,它仍然记录形成时间,而不是时间,我把它扔在你。放射性的时钟撞击地球不重置在陨石的矿物质。>岂不是更准确的通过其内部材料吗?它会。 There is just one problem - we don't have materials from the time of Earth's formation. The Earth is a dynamic place, and rocks are getting formed and destroyed all the time (also see [related question][1]). It may be that such old rocks exist on Earth, but because they are so old there are either metamorphosed and buried deep in the Earth or covered by sedimentary rocks. The oldest exposed rock on Earth available for study is the 4 billion year Acasta Gneiss in Canada. The oldest mineral on Earth is a zircon found in Australia, which is 4.4 billion years old. These are the only two materials that are known to be older than 4 billion years on Earth. There could be more, but we just couldn't find them. This is why meteorites are excellent for this task - they mostly formed during the formation of the Solar System. [1]: //www.hoelymoley.com/q/773/725
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