Geology deals with the composition of Earth materials, Earth structures, and Earth processes.

地质学研究地球的物质组成、地球的结构及地球的形成过程。

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When you analyze this light, you can figure out their distance from the Earth, and identify what they are made of, determine their chemical composition.

当你分析这些光的时候，你可以计算出它们与地球的距离，并确定它们由什么构成，查明它们的化学成分。

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The once-secret lives of plants are telling researchers volumes about the composition of Earth's atmosphere, providing clues to past and current climate change.

CNN: Plants spread secrets about climate change

"The text of the Clean Air Act makes plain that Congress intended it as a measure to 'clean' the air of pollutants, not to alter the overall composition of the Earth's atmosphere, " argues the Alliance of Automobile Manufacturers, an auto industry lobbying group, in a brief.

FORBES: Supreme Court Takes On Global Warming?

But the early models indicated that much of this debris would have originated from the impactor, whose composition would most probably have differed substantially from that of Earth.

BBC: Moon formation: New spins put on old questions