单选题 .  ①One reason researchers have long believed that Mars never enjoyed an extensive period of warm and wet climate is that much of the surface not covered by wind-borne dust appear to be composed of unweathered material. ②If water flowed for an extended period, researchers reasoned, it should have altered and weathered the volcanic minerals, creating clays or other oxidized, hydrated phases (minerals that incorporate water molecules in their crystal structure).
    ①It turns out, though, that the scientists were not looking closely enough. ②New high-resolution mapping data and close-up surface studies have revealed clays and other hydrated minerals in many regions. ③The clay deposits are scattered all over, in ancient volcanic surfaces and heavily cratered highland regions, some of which have apparently been exposed by erosion only recently.37.  According to the passage, scientists are able to discover weathered material on the Martian surface because they have benefited from which of the following? ______