GMAT考试资料：GWD试题合集（五十四）.

　　以下将为正在备战GMAT考试的同学们整理一些经典的GMAT阅读试题，并分多个合集推出，希望能够为正在备考GMAT考试的考生提供或多或少的帮助。

　　30. GWD-30-Q11-Q13 最老的火山岩石和发现它的科学意义

　　First identified in 1969, komatiites

　　are Earth’s oldest known volcanic

　　rocks and contain three times as much

　　Line magnesium as do most volcanic rocks.

　　(5) This chemical composition suggests

　　that komatiites formed from the hottest

　　lava known ever to have erupted: a

　　high concentration of magnesium

　　changes the physical properties of

　　(10) lava so that unusually high tempera-

　　tures would be required for the lava

　　to exist as a liquid.

　　Komatiites’ discovery was surpris-

　　ing in light of then-current geological

　　(15) theories about magmas, molten rock

　　that forms in the Earth’s mantle (the

　　layer beneath the crust) and composes

　　volcanic lava eruptions. Prior to 1960,

　　geologists Bowen and Hess disagreed

　　(20) over whether or not the very high tem-

　　peratures needed to produce magmas

　　rich in magnesium could have existed

　　on Earth. Hess suggested that the

　　presence of water, probably released

　　(25) from minerals decomposing in the

　　Earth’s mantle, might have meant that

　　a high-magnesium magma could have

　　existed at a lower temperature. But

　　Bowen showed experimentally that the

　　(30) high temperatures were indeed nec-

　　essary. By 1960, it was generally

　　accepted that volcanic rocks with such

　　high levels of magnesium could not

　　exist, and thus the discovery of koma-

　　(35) tiites changed geologists’ assumptions

　　about the characteristics of the Earth’s

　　mantle around the time of the formation

　　of komatiites, between 2.5 and 4 billion

　　years ago.

　　以上就是本期GMAT试题的所有内容，考生可以此为据并进行针对性的练习，逐步掌握GMAT阅读的解题规律及技巧，以达到迅速提高GMAT考试成绩的目的。 相关链接：

1.GMAT考试资料：GWD试题合集（五十三）

2.GMAT考试资料：GWD试题合集（五十二）

3.GMAT考试资料：GWD试题合集（五十一）

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