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Iturralde Crater (also called Araona Crater) is a 5-mile (8 km) diameter circular feature in the Bolivian portion of the Amazon Rainforest, first identified from Landsat satellite imagery in 1985.〔(NASA Educational Brief ). Retrieved on 2007-02-19.〕〔(Goddard Scientific Visualization Studio ). Retrieved on 2007-02-19.〕 Being so circular, it is argued by some scientists that it may be a meteorite impact crater. Because it is in an area of active sediment accumulation by rivers, it must be a geologically young feature, with estimates of its age ranging between 11,000 and 30,000 years.〔 Unlike other young craters, it is very flat, so if it is of impact origin, perhaps the crater sunk into the soft sediments leaving only a circular 'ghost' marking the original rim. The site is very remote, but has been visited twice by scientific investigators, most recently by a team from NASA's Goddard Space Flight Center in September 2002.〔(ICE2002 Expedition ). Retrieved on 2007-02-19.〕〔('Top Story' at Goddard Space Science Center ). Retrieved on 2007-02-19.〕 In both cases, the expeditions failed to find conclusive evidence for the origin of the feature. == References == 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Iturralde Crater」の詳細全文を読む スポンサード リンク
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