RT @Geology_History: May 24, 1869, the first expedition to map and study the Gran Canyon lead by explorer and geologist John Wesley Powell…
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RT @Geology_History: May 24, 1869, the first expedition to map and study the Gran Canyon lead by explorer and geologist John Wesley Powell…
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RT @Geology_History: May 24, 1869, the first expedition to map and study the Gran Canyon lead by explorer and geologist John Wesley Powell…
2,093 followers
RT @Geology_History: May 24, 1869, the first expedition to map and study the Gran Canyon lead by explorer and geologist John Wesley Powell…