Landsat 7's Enhanced Thematic Mapper Plus (ETM+) sensor image of snowcapped Chimborazo (left), and the smoking Tungurahua Volcano on the right. In this false-colour image, pale blue indicates snow cover, bright green indicates lush vegetation, and red indicates sparser vegetation. Tungurahua's volcanic ash plume appears in lavender. This steep-sloped volcano is one of Ecuador's most active volcanoes; an eruption beginning in 1995 forced a temporary evacuation of a nearby city, situated at the volcano's base. In 1802, Mount Chimborazo was thought to be the world's tallest mountain, but the German naturalist Alexander von Humboldt, who tried to climb up the side of Chimborazo, changed the way naturalists thought about altitude, vegetation and volcanoes.
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