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Saint Helena, Ascension, and Tristan da Cunha

Saint Helena's rugged topography of sharp peaks and deep ravines – evident in this photograph from the International Space Station – is the result of erosion of the volcanic rocks that make up the island. A climatic gradient related to elevation is also evident – the higher, wetter central portion of the island is covered with green vegetation, whereas the lower coastal areas are drier and hotter with little vegetation cover. Image courtesy of NASA.