新GRE阅读真题解之火星的风蚀.doc

新GRE阅读真题解析之火星的风蚀
新GRE阅读真题解析之火星的风蚀。下面为大家汇总了新GRE阅读考试真题,主要是关于火星风蚀的相关内容,供同学们进行下载练****br/>GRE阅读考试真题之火星的风蚀
One reason researchers have long believed that Marsnever enjoyed an extensive period of warm and wetclimate is that much of the surface not covered bywind-borne dust appear to posed ofunweathered material. If water flowed for anextended period, researchers reasoned, it shouldhave altered and weathered the volcanic minerals,creating clays or other oxidized, hydrated phases(minerals that incorporate water molecules in theircrystal structure).
It turns out, though, that the scientists were notlooking closely enough. New high-resolution mapping data and close-up surface studies haverevealed clays and other hydrated minerals in many regions. The clay deposits are scattered allover, in ancient volcanic surfaces and heavily cratered highland regions, some of which haveapparently been exposed by erosion only recently.
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