|
Navidad Formation ((スペイン語:Formación Navidad)) is a marine Neogene sedimentary formation located in Central Chile.〔 The formation is known for its diverse and abundant fossil record and is considered the reference unit for the marine Neogene in Chile.〔〔 Originally described by Charles Darwin in 1846 the formation has attracted the attention of numerous prominent geologists and paleontologists since then. As a key formation Navidad has been subject to a series of differing interpretations and scientific disputes over time. ==History== Charles Darwin saw the formation in September 1834 during the second voyage of HMS Beagle. He became the first to described it 1846 when he published his book Geological Observations on South America in 1846 and is was named by Darwin after the nearby town of Navidad. In this book Darwin calls the formation "Formation of Navidad" and "Sandstone Formation at Navidad". There are no signs of that Darwin would have attempted to make a formal definition of the formation.〔 Early fossil descriptions from Navidad Formation were those of George Sowerby in ''Geological Observations on South America'' (1846) and by Rodolfo Amando Philippi (1887).〔 Gustav Steinmann redefined the Navidad Formation in 1895, then called Piso Navidad, by giving it a Lower Tertiary age and spanning much of south-central Chile. In 1934 Juan Brüggen separated Piso Concepción from Steinmanns Piso Navidad after showing there was a discordance between them.〔 Juan Tavera further narrowed the age of the formation in 1968 and 1979 by proposing a Burdigalian (Lower Miocene) age for Navidad, Lincancheo and Rapel which were then the three subunits of Navidad Formation. Tavera's 1979 subdivision scheme for Navidad Formation remained popular until it was superseded in 2006 by a new one.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Navidad Formation」の詳細全文を読む スポンサード リンク
|