An International Space Station astronaut took this snapshot of Santiago in the Galápagos Islands when the station passed about 250 miles (400 kilometers) overhead on October 28. The bird's-eye view shows some of the geologic processes that created the islands over a volcanic mantle plume, or hot spot.
Santiago was formed by a shield volcano, whose low, flat summit ridge is seen below the green vegetation that covers the volcano's south-facing slopes (top left). Shield volcanoes produce extensive lava flows—here lava is visible as dark patches along some coastlines.
Tuff cones, seen as small circles at upper right, are created when hot lava turns the water below to steam, which then explodes up through the lava and scatters it.
Santiago - the capital of Chile
mantle - the structure of the earth, crust, mantle and core
mantle plume - 地幔热柱
ridge - 山脊，线形隆起 the ridge of the nose 鼻梁
lava - 熔岩
patch - 补丁，碎屑，斑点，文章的一段
Tuff - 凝灰岩 Sedimentary（沉积岩） > Pyroclastic（火山碎屑岩） > Tuff
cone - 圆锥，火山锥
explode - 爆发，激增
scatter - 散开，分散
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