They would leave subtle clues in the isotopic composition of the limestone by shifting the ratios of light to heavy carbon and oxygen atoms in its calcium carbonate.

因为如果是那样的话，阳光将会被转换成大量的碳、氧原子保存到石灰岩中的碳酸钙里，而事实却是，岩层的同位素组成（Isotopic composition）中没有留下任何蛛丝马迹。

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The trick they used to do this was to look at the isotopic composition of the oxygen in the wood of local trees.

他们所使用的办法是观测当地树木的木材中的氧同位素组成（isotopic composition）。

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Now, by examining the isotopic composition of that water, researchers have found that it matches that of meteorites, the likes of which also delivered Earth its first drink.

现在，通过检查水的同位素构成，研究人员发现这与第一次给地球带来水的陨石相吻合。

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By analysing the isotopic composition of hydrocarbon molecules from plant waxes of the period, he found what looks like a spike in the amount of recently non-biological carbon (which has a distinctive ratio of light isotopes to heavy ones), lasting between 10, 000 and 20, 000 years.

ECONOMIST: A geological burp may have led to the dinosaurs�� domination