They bear a strong resemblance to river systems on Earth, and geologists think that they are dried-up beds of long-gone rivers.

它们与地球上的河流系统非常相似，地质学家认为它们是早已消失的河流留下的干涸的河床。

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Shortly after this the famous H. M. s. Challenger expedition established the study of the sea-floor as a subject worthy of the most qualified physicists and geologists.

此后不久，英国著名的“挑战者”号舰艇对海底的那次考察，把对海床的研究确立为一个值得一流物理学家和地质学家从事的研究课题。

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Scientists, such as astronomers and geologists, understand this very well.

科学家，天文学家和地质学家都十分清楚明了这一点。

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They include biologists,astronomers, physicists and geologists.

VOA: special.2009.06.03

And geologists and hydrologists fret about the possibility that dissolved metals might get into water supplies.

ECONOMIST: Energy supplies

Apart from continent-hopping business executives, niche markets include long-haul truckers, civil engineers, field scientists, disaster-relief agencies, news organisations, extractive industries and geologists.

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Mount Rainier is also an active volcano - although there has been no activity since the 1850s and geologists say there is no imminent threat of eruption.

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