notes: antarctica, secrets of the southern continent, by david mcgonigal

antarctica: secrets of the southern continent, chief consultant david mcgonigal, firefly books 2008

“the antarctic peninsula formed as a volcanic arc during the mesozoic era (248-65 mya).  by 30 million years ago, in the mid-cenozoic, south america stretched northward from antarctica, became disrupted, and formed the small, new plate of the scotia sea.  the very active volcanoes of the south sandwich islands at the easternmost end of the scotia plate mark its collision with an oceanic plate to the east.” p25

“around 50 to 60 million years ago, australia was separated by rift-faulting.  the final phase in antarctica’s isolation was its stretching apart from south america about 35 to 40 million years ago, during the formation of the scotia sea.  growth of that new sea, as well as the southeastern indian ocean, had important climatic and biological consequences in the ensuing development of one of the earth’s greatest currents, the southern ocean’s circumpolar current, also known as the west wind drift.  this current kept warm northern waters from reaching the coasts of antarctica and, it is believed, it allowed the growth of the ice sheets.  the migration routes of animals such as early marsupials were cut off.  fossils of a number of species of dinosaurs found in antarctica – some near-cousins of australian species – show that such migration routes had extended far back in to mesozoic times.” p29

“australia’s separation from antarctica began in the late cretaceous period, although opportunities for plants and animals to cross water gaps might have persisted for a long time after that.  the drake passage probably began to open about 23 to 25 million years ago, but there is little information about how much dry land there was between the antarctic peninsula and south america before then.” p33

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About jeanne

artist, grandma, alien

Posted on June 12, 2010, in antarctica, research. Bookmark the permalink. Leave a comment.

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